PURPOSE. It is very important to localize the short circuit in case of power line failure. A significant percentage of power lines damage belongs to single-phase short circuits accompanied by phase breaks. This paper proposes the methods for determining the locations on the lines in networks with a grounded neutral using instantaneous values of industrial frequency parameters. METHODS. The studies are carried out according to the programs simulating transients under short circuits accompanied by the appearance of aperiodic components in currents. RESULTS AND THEIR DISCUSSION. An algorithm is proposed for a one-way determination method of a transmission line phase break location that is based on the processing of instantaneous values of currents and voltages. An algorithm for the elimination of aperiodic components from measured currents is proposed and researched. CONCLUSIONS. The measurement time will not exceed 2.5 ms under the sampling interval of 0.5-0.625 ms. Magnetic cores of current transformers will not saturate during this time. It means that relay protection receives undistorted information and it is possible to determine the location of the power line phase break by measuring the instantaneous values of phase currents and voltages of the line section without short circuit.

PURPOSE. Today it is impossible to design and operate low-voltage networks without the creation of methods of mode computer simulation. However, the basic works in this direction are devoted to high voltage networks and do not take into account the features of low voltage networks up to 1000 V. The purpose of the researches, the results of which are presented in the article, consists in the development of methods and tools for adequate simulation of electrical power supply system containing 0.4 kV bus bars with large buses. METHODS. The methods of electrical power system simulation in phase coordinates have been used to determine the modes of electric power supply systems (EPSS) equipped with bus bars. The methods applied are based on the representation of multiwire elements of lattice equivalent circuits with full-meshed topology. The proposed simulation method of EPSS with bus bars allows to consider the real distribution of currents on bus sections, the skin effect, the proximity effect as well as the availability of metal boxes for bus placement. The main idea of the method is the change of buses by a set of thin wires whose joint current is equal to the bus current. RESULTS. The introduced simulation method of bus bars with rectangular buses allows to implement the system approach to EPSS mode determination and provides the opportunity of correct consideration of the skin and proximity effects when mode calculation. The adequacy of the method is confirmed by the agreement of simulation results and experimental data. Magnetic fields can be created in the proximity to the non-shielded bus bar. Their strengths considerably exceed the normalized values. Bus bars with bundled phases create especially high strength levels. The use of rational phasing allows to reduce the strength value. CONCLUSION. Computer simulation has shown that the use of multiwire models provides correct accounting of skin and proximity effects when used for mode calculation of networks with bus bars.

The PURPOSE of the paper is to perform an energy-economic analysis of the Irkutsk region on the basis of fuel and energy balances, identify the most significant factors affecting energy efficiency and reveal the potential for regional growth. METHODS. The study uses a methodical approach developed by the authors and based on the methods of economic and mathematical modeling, system analysis, correlation and regression analysis, balance methods. The methodological approach develops existing knowledge in the given subject area. RESULTS AND THEIR DISCUSSION. The role of the Irkutsk region fuel and energy complex is shown in Russia and in the Siberian Federal District. Report fuel and energy balances are generated. Based on the performed energy-economic analysis the most significant factors affecting energy efficiency have been identified. Comparative analysis with the all-Russian indicators has allowed to reveal the potential for energy efficiency growth. CONCLUSIONS. The main factors affecting the growth of regional energy efficiency include the use of innovative technological processes and equipment, reduction of energy losses; structural changes in the fuel and energy balance involving the increase of the percentage of natural gas and renewable energy sources. Their implementation can potentially give a significant economic effect of up to $300 million annually.

PURPOSE. The paper describes a two-stage approach to the selection of the territories for the implementation of high priority measures to improve energy efficiency in the regional municipal heat supply systems. METHODS. The current state of the Irkutsk region municipal heat supply sector was subjected to the analytical studies and ranking. Using a two-level methodical approach oriented to the main criterial indicators of area operation efficiency the territories for the implementation of high priority measures in the municipal heat supply systems were determined. RESULTS AND THEIR DISCUSSION. The regional municipal heat supply sector is characterized, the problems are analyzed and the tasks for their elimination are set. A methodical approach is proposed allowing to identify the most troubled territories for the implementation of necessary measures to improve the situation. Indicators, which are quite sensitive for consumers and the budget including tariffs, subsidies, fuel costs and others, are used as criteria. The paper proposes promising directions of modernization and efficiency improvement of the systems within which high priority measures are planned to be implemented in order to ensure the optimal operation and development of the municipal heat supply sector of the region under investigation. CONCLUSIONS. In accordance with the tasks for ensuring high efficiency level of municipal heat supply sector operation in the region the main development directions for the communal heat supply sector have been formulated with the focus on the innovative transformations.

PURPOSE. Development of small distributed generation included in the network of low and average voltage sets the task of effective voltage regulation off-line the operating emergency control by means of the decentralized automated control. Multiagent control (MAC) is the means of solving this problem as every intelligent regulator included in the MA system can represent the interests (be an agent) of the subjects of the overall process of power supply (network company, small generation, a consumer) and the voltage mode is determined as a compromise of their interests. METHODS. The proposed method for solving this problem is based on the unified basic rules of decision-making and implementation of agents’ actions taking into account the controlled area mode and coordination of actions with neighboring agents. RESULTS AND THEIR DISCUSSION. The paper formulates the problem of multiagent compromise voltage regulation in active (in general) multiconnected electrical networks. Consideration is given to a one-level system of multiagent regulation with intelligent agents featuring both their own decision-making area (the area adjoining to the electrical network) as well as forming an expanded area of concerted actions. To control the adjacent area mode the agent uses only local mode parameters. The agents exchange data through the channels of direct electrical connections between the network nodes. The structure of a multi-agent voltage regulator is proposed and the need for an intelligent (expert) block in its composition is substantiated. CONCLUSIONS. The possibility of compromise voltage control in electrical networks with distributed means of reactive power compensation using a decentralized multiagent system coordinating agents’ actions in neighboring areas is proved.

The PURPOSE of the paper is to study the effect of feed at the end cylindrical milling under conditions of self-oscillations on the formation of machined surface profile. METHODS. The study is based on the experimental research methods that enable the examination of the influence of technological factors on the oscillatory processes occurring in the cutting zone. The method of dividing the oscillograms obtained at milling into the basic fragments that reflect the shape of the cutting surface allows to analyze the shaping of the treated surface. RESULTS AND THEIR DISCUSSION. The relationship between the feed and waviness parameters of the treated surface at end cylindrical milling under conditions of self-oscillations is shown experimentally using the basic fragments of oscillograms for the analysis of cutting surfaces. It is determined that the pitch and waviness height on the treated surface reduce as the feed is increased. This is due to the decrease in the period and amplitude of self-oscillations which determine the geometry of the wavy track on the cutting surface. Correlation dependences between the feed, the period of self-oscillations, the pitch and the waviness height of the treated surface are determined. CONCLUSIONS. At the end cylindrical milling under conditions of self-oscillations an increase in feed rate leads to a decrease in the pitch and waviness height of the machined surface. The obtained regression equations can be used at the design stage of the technological process to assess the effect of the set feed on the treated surface.

The article deals with the dynamic properties of a technical object with two degrees of freedom in the modes of dynamic damping of oscillations. The technologies are introduced for transfer function construction and determination of conditions for dynamic damping of oscillations. The PURPOSE of the work is to develop a construction method of mathematical models assessing dynamic properties and determining the implementation conditions of dynamic effects of motion nulling by individual coordinates. METHODS. The study uses the methods of structural mathematical modeling. The scientific novelty of the work is in the evaluation of the applicability of motion transformation devices in the structures of mechanical oscillating systems. The transition technology from transfer functions of oscillatory systems to equations has been developed in order to estimate the frequencies of dynamic damping of oscillations. The frequency of dynamic damping of oscillations is determined from the conditions of nulling the numerator of the system transfer function. It allows to form an approach for the identification and evaluation of the features of the modes of dynamic damping of oscillations and is connected with the fact that external kinematic perturbation of the object simultaneously excite both partial systems. RESULTS. The algorithms are proposed to construct frequency diagrams for finding the required frequency of dynamic damping of oscillations. The system is shown to have the potential to implement different modes of dynamic damping of oscillations. The simultaneous damping of oscillations by two coordinates can be implemented only at one frequency of the external disturbance. CONCLUSIONS. The obtained results are of interest to a wide range of specialists engaged in solving the problems of control of the dynamic state of technological vibration machines, dynamics and strength of equipment, tools and devices under intense dynamic loading.

The PURPOSE of the paper is to improve the production efficiency of long-size double curvature skins of aircrafts based on the control of the stress-strain state under automated technological process of shot peening. The following steps are required in order to achieve the set purpose: to improve the calculation accuracy of the internal force factors of the shot blasting process that directly depend on the processing modes and determine the deformation of the processed part; to develop a methodology for process parameters calculation that will allow to increase the degree of conformity to the theoretical contour of the part shape resulting from the rough forming; to provide the conditions for the automation of part final shaping operations; to develop technological methods aimed at increasing the shaping performance of double-curvature sections; solve a number of technical issues on the automation of auxiliary operations that are responsible for significant raise in labour intensity; take measures to ensure the stability of the shot blasting process under the implementation of the control program. The METHODS applied include modeling using nonlinear finite element analysis, study of the machined surface micro-relief using a 3D optical profilometer, measurement of the curvature of samples using electronic indicating devices. RESULTS AND THEIR DISCUSSION. The procedure is proposed to determine internal force factors of shot peening by the finite-element modeling of the process of multiple indentation of shots with different speeds and trajectory inclination angles in the machined part material. The methods have been developed to determine the conditions of the technological process of shot blasting on contact type installations in the automated control mode taking into account the effect of the stress-strain state of the workpiece and the control results of the intermediate shape of the part. The design and software solutions aimed at ensuring the implementation of the automated process of shot blasting forming are proposed. Based on the performed theoretical and experimental researches the calculation methods of technological parameters of shot peening operations for rough forming of double curvature parts have been developed. They take into consideration the influence of the stress-strain state and control of the workpiece shape under forming and finishing treatment on the basis of the results of control of the workpiece intermediate shape.

The PURPOSE of the study is to analyze the welding of high-strength rail steels for continuous welded rail in terms of structure formation in the welded rail joint performed in Russia and abroad. METHODS. Various technologies of rail welding are compared and analyzed. The structural factor in the welded rail joint is analyzed on the basis of metallographic studies. RESULTS AND THEIR DISCUSSION. Consideration is given to the main research directions and the results obtained by different authors in the field of rail welding. Analysis is given to the requirements for the continuous rail track in the field of welding for various technological methods (aluminothermic welding, flash butt resistance welding, gas pressure welding, friction welding, manual arc welding). The works are analyzed taking into account the received structures in the welding joint and the zone of thermal influence for the main methods of rail welding including aluminothermic, gas pressure, resistance flash welding, linear friction method, electric arc, and electroslag methods. The macrostructures and hardness of the welded rail joint are compared for the welding methods under investigation. In addition, the rail welding technologies introduced on the Russian and foreign rail roads are analyzed. CONCLUSIONS. It is shown that in terms of the structural factor, low values of impact resilience and crack resistance at negative temperatures, high level of defect formation in the rail joint, the aluminothermic welding of rails can not be recommended for the construction and reconstruction of high-speed continuous welded rail roads. This method does not provide high quality of the rail joint and reduces traffic safety. Other methods of rail welding provide high quality of the rail joint and are more promising according to the physical and mechanical properties in the welded joint. However, it is required to conduct additional studies of the processes of structure formation in the welded joint and the zone of thermal influence under conditions of negative temperatures and high specific loads on the rail joint.

The PURPOSE of the paper is experimental study of the carbonization of alkaline aluminate solutions and search for the region of available technological regimes to obtain the precipitation of a high dispersity aluminum hydroxide. METHODS. The study uses the following analysis methods: multifactorial experimental study of the carbonization indices of aluminate solutions and calcination of their decomposition products, laser microanalysis of particle size and size distribution, spectral analysis of gas-air mixture composition, electron microscopy of precipitation composition and chemical analysis of solutions, mathematical processing of results. RESULTS. The process temperature and solution neutralization rate are shown to be of decisive importance when obtaining the products of high dispersity. The dependence of the average median diameter of precipitate particles for aluminum hydroxide crystallization in the form of bayerite and gibbsite has been obtained in the form of a second-order polynomial. It has been determined that the average size of gibbsite particles changes at the stage of high-temperature calcination depending on the heating rate and isothermal temperature that is accompanied by slight agglomeration and an increase in their size. CONCLUSION. Technological principles of obtaining finely dispersed materials under nepheline raw materials processing formulated in the article provide the opportunity to adapt the carbonization process for the production of non-metallurgical products.

The PURPOSE of the paper is to study the equilibrium in the system ion-exchanger TP-220 - copper-containing solution and kinetic characteristics of Lewatit TP-220 ion-exchanger as applied to the solution after the nitric acid leaching of the copper concentrate of the unpayable ore of the Zhezkazgan deposit. METHODS. Static experiments were carried out to determine sorption equilibrium. Static sorption was conducted in glass jars where the phases were mixed by mechanical agitators. The sample of the sorbent was treated for a certain time by the initial solution at the temperature of 75°C. At the end of the process the phases were separated. The solutions were sampled to analyze the content of copper and other cations. The saturated sorbent was washed with water and analyzed for the content of main components. RESULTS AND THEIR DISCUSSION. It has been determined that the isotherm of copper sorption by ion-exchanger TP-220 confirms high sorption capacity even at extremely low concentrations of copper in the initial solution. The temperature factor in the range from 20 to 50⁰С at a contact time of phases more than 60 minutes does not have any noticeable effect on the ion exchange parameters of the sorbent. CONCLUSIONS. The sorption of copper on the sorbent under investigation features high rate that ensures its maximum capacity even after 60 minute contact at room temperature, i.е. sorbent has good kinetic properties of copper sorption.

The PURPOSE of the paper is determination of the influence regularities of mechanochemical activation parameters on the particle size and properties of hot-deformed powder materials (HDPM) that are based on activated chip powder D16 with the addition of ferrotitanium. METHODS. Combined mechanochemical activation of chip D16 and ferrotitanium was carried out in the saturated aqueous solution of boric acid (SASBA) in a planetary ball mill SAND-1 at different processing times and grinding rates. The particle size distribution of charge followed by its processing in a hand mixer was studied and the agglomeration parameter was determined. The resulting charge was divided into fractions; one part was mixed with aluminum powder; subjected to cold moulding followed by short-term heating and forming. Hardness, ultimate shear strength and ultimate bending strength of hot-deformed powder materials were also determined. RESULTS AND THEIR DISCUSSION. 3D spline models of the activated chip powder (ACP) yield dependence on grinding time and rate have been constructed. Introduction of 30% saturated aqueous solution of boric acid of the charge weight into the grinding media provides better grinding estimated by the amount of yield of the activated chip powder. Using Rosin-Rammler equation the correspondence to the normal distribution law has been revealed for the particles of this charge. The integral curves of particle size distribution after the mechanochemical activation and manual processing have been constructed. CONCLUSIONS. The optimal parameters of mechanochemical activation are determined. They provide a higher yield of the activated chip powder. The resulting charge is characterized by a minimum average particle sizes and the increased value of the agglomeration parameter. The obtained materials have increased values of the ultimate shear strength (249 MPa), hardness (102 HRE) under the bending strength of σ_b = 179 MPa. An improved technology is proposed for the production of hot-deformed powder materials based on mechanochemically activated chip powder with the addition of ferrotitanium.

The PURPOSE of the work is to evaluate the importance level of parameter influence on the accuracy of solar heating system mathematical modeling. METHODS. The numerical modeling of solar heating system operation is carried out in accordance with the fractional factorial designs under different combinations of parameters affecting its operation. The importance of the parameters under investigation is determined by means of variance analysis. RESULTS AND THEIR DISCUSSION. The analysis of parameters influencing the operation of solar heating systems allowed to distinguish two groups: construction parameters and calculation parameters. The calculation parameters affect the accuracy of the model of system operation. Using fractional factorial design, eight numerical experiments were planned and carried out under similar initial conditions (fixed construction parameters) and different combinations of calculation parameters using the Yates algorithm. Conducted numerical experiments allowed to determine the degree of parameter influence for different output characteristics. The latter are treated as indicators of system efficiency including the time of pump operation, amount of heat transferred to water in the storage tank, duration of the period when the user is provided with hot water. CONCLUSIONS. The more number of parameters are taken into account when modeling solar heating systems, the more accuracy of results is achieved. When the construction parameters are specified the most important parameters are the heat transfer coefficient of the storage tank heat exchanger and heat losses of external elements of the system. It is recommended to take into account these two calculation parameters while the primary physical properties of media and heat losses of internal elements of the system can be neglected when modeling solar heating systems.

PURPOSE. The work deals with the creation of flexible and universal mathematical support and software for solving reliability problems using a structural reliability scheme based on Simulink. METHODS. Using the known analysis methods of structural reliability schemes some general methodological approaches and principles of software construction have been developed as a separate add-on (Toolbox) for Simulink. Algorithms and programs for calculating the reliability characteristics of individual elements of the technical system and the system as a whole have been developed. The algorithms and programs are unified, grouped by purpose and designed for the formation of mathematical models of complex systems. RESULTS. The article presents some examples of the designed unified blocks, which get a full picture of the developed software and methodological principles of its application. Using the example of a simple structural reliability diagram of five elements, the capabilities of the proposed Toolbox for modeling complex structural reliability schemes are demonstrated. CONCLUSIONS. The proposed software allows to develop mathematical models of structural reliability schemes of any complexity, perform a computational experiment in order to analyze their characteristics and evaluate the efficiency of measures to improve the reliability of systems. The software enables to modify the mathematical models in a fairly simple way, to organize a programming interface and process simulation results. The software is an extremely effective to be used in professional education due to the visibility and informative nature of mathematical modeling in reliability problems.

PURPOSE. It is a well known fact that proportional integral (PI) and proportional integral derivative (PID) controllers when applied in automatic systems with a large delay (when the delay value exceeds the highest values of controlled object time constants) do not provide acceptable quality of transients. This makes us address to some classes of regulators compensating the negative impacts of delay. This article deals with the known for its advantages PID controller with semi-permanent integration that belongs to the class of regulators with a variable structure that do not use a sliding mode. On the basis of the minimum integral-square criterion this work forms the algorithm of an automatic parametric optimization (APO) that calculates the optimal adjustment vector of the PI-controller with semi-permanent integration in an automatic system for the object with a large delay when adjustable parameters of the controller are independent from the moment of switching. METHODS. Due to the fact that the controller applied belongs to the class of regulators with a variable structure and the study is devoted to an object with delay, the use of analytical approaches to the adjustment of such regulator is extremely difficult. Therefore, an algorithmic method should be used to solve the problem of controller parametric optimization. This study also employs a gradient procedure which enables to calculate gradient components using the functions of sensitivity with their known advantages. RESULTS AND THEIR DISCUSSION. The formed APO algorithm has determined the optimal parameters of the PI controller with semi-permanent integration for a given object with a large delay at the minimal integral-quadratic criterion. The validity of the found vector of controller adjustment generated by the APO algorithm is confirmed by the calculation of Hessian matrix and proven by the computing methodology. CONCLUSIONS. The APO algorithm solves the set problem of parametric optimization with the accuracy sufficient for practice. Received positive experience in the optimization of PI-controller with semi-permanent integration allows to apply it to other regulators with variable structure that do not use the sliding mode. In future it will allow to extend the use of the gradient algorithm based on the sensitivity functions for this class of controllers with variable structure under different laws of controller structure switching.

The PURPOSE of the study is to develop the methodology for estimating the program execution time in a heterogeneous distributed computing environment. Today, the problem of obtaining such estimation is important and nontrivial in many practical applications related to the computation planning and resource allocation. METHODS. The study uses the method of frequency response characteristics that is based on the use of special tools for the dynamic analysis of programs. It has well proved itself in practice. RESULTS. A new methodology is proposed that provides program execution time estimation and takes into account the characteristics of reference and target computational nodes as well as software parameters that reflect the computational load on the components of these nodes. The estimates are calculated based on the amount of input data. This methodology has been successfully applied when analyzing the program execution for solving the problem of matrix multiplication. The paper provides the test cases of obtaining the time estimation of such problems solution in which the error is less than 10%. The obtained results demonstrate that the estimation error decreases as the dimension of matrices (both for integer and real values) grows. CONCLUSIONS. The proposed technique was used for the real job flow in the heterogeneous distributed computing environment based on the resources of the public access computer center “Irkutsk Supercomputer Center SB RAS”. Its application showed the significant improvement in the obtained estimations of the program execution time as compared with the estimates of the required time for solving the problems in users’ queries, as well as their values corrected on the basis of the computational history of executed jobs.

PURPOSE. Construction of the random effect gamma degradation model results in the enlarged dimension of the vector of estimated parameters. Therefore, it is necessary to understand whether the introduction of the random effect allows to obtain more accurate estimates of model parameters or not. The paper compares the fixed effect and random effect gamma degradation models in terms of the estimation accuracy of their parameters. METHODS. The estimation accuracy of the highest likelihood of degradation model parameters is studied through the calculation of the Euclidean norm of the relative error of the obtained estimates for the different values of random effect based on the Monte-Carlo method. RESULTS AND THEIR DISCUSSION. The estimation accuracy of parameters is higher for the random effect degradation model with the increase of the random effect value. However, if unit-to-unit variability coefficient does not exceed 0.1, it is recommended to use the fixed effect degradation model for the higher estimation accuracy of model parameters. MAIN CONCLUSIONS. It is shown that the use of the random effect gamma degradation model is not advisable in the case of small sample volumes and an insignificant random effect.

PURPOSE. The article presents the results of the study of public passenger transportation system in Seoul (South Korea). It deals with the issues of passenger transportation organization in Seoul including automated fare collection system, availability of special plastic cards and their operation principle, which can become a technological basis for improving the quality of public transport services. METHODS. The article presents the results of marketing research of the organization and operation of public municipal passenger transport in the city of Seoul conducted by the Department of Motor Transport of Irkutsk national research technical university. An integrated analysis is given to the market of transport services. Primary and secondary data have been collected through field researches. The feature of the work is a direct and comprehensive study of the real city transport infrastructure as a marketing object. RESULTS. There is the possibility to use the Korean experience in the organization and management of urban transportation systems of Russian cities in order to improve passenger transportation in big urban centers. This will improve the efficiency and quality of population servicing as well as provide an opportunity to establish reasonable transportation tariffs. The effectiveness of Korean innovations in Seoul transport system proves the fact that the population of the city and its suburbs is switching from private cars to public transport. As a result the transport load has been reducing and the traffic volume has been increasing for a number of years. CONCLUSIONS. The following conclusions have been derived as a result of the analysis of marketing researches of public passenger transport organization and operation in Seoul. Non-cash automated fare collection system serves as a technological basis for the improvement of passenger transport servicing quality. The use of the automated fare collection system on Seoul ground transport allows to take into account the provision of benefits, to date transport companies by natural indicators of performed passenger traffic volume, to reduce the load on the city transport system, to increase the number of passengers through switching them from personal cars to public passenger transport and thereby increase the income of carriers, to monitor and control the quality of services provided by transport companies, to receive the information for decision-making on the development of public passenger transport and passenger transportation tariffs. Moreover, the automated fare collection system provides information on inter-stop (inter-node) travels and allows to detail the need for trips by public passenger transport.

PURPOSE. This paper develops a structural algorithm to automate the processes of efficiency control and monitoring of the condition of track circuits through the use of wideband signals able to provide a substantial increase of qualitative indicators of control of railway transportation safety indicators. The automation of rail circuit efficiency control is implemented by the system of blocks responsible for performing a certain task in the form of a structural model of FILAC (F-functional subsystem; I - information subsystem, L - logical subsystem, A - addressing subsystem, C - control subsystem). This model allows to create a system for the implementation of any algorithmic process of control, diagnosis and management, being the basis for the creation of the required one. METHODS. The study is based on the method of development and analysis of the automation algorithm of the processes of efficiency control and monitoring of the rail circuit condition through the use of broadband signals. It will significantly improve the qualitative indicators of control of rail transportation safety parameters. RESULTS. CONCLUSIONS. Application of new control methods and a special automation algorithm of the rail circuit efficiency control system that provides rail traffic safety through the use of radio signals will significantly improve traffic safety indicators and operation reliability as well as decrease energy costs and other. It should be noted that the new approach can significantly reduce the delay time of trains.

PURPOSE. When carrying out road accident expertise today the values of vehicle deceleration are used. The latter were established in 1995 by the methodological recommendation of the Russian Federal center of forensic expertise for different categories of vehicles without taking into account the temperature of the asphalt-concrete pavement surface and specific characteristics of a particular vehicle. The problem of determining the longitudinal coefficient of vehicle wheel tire adhesion to the road surface reduces the quality of automotive expert examinations. The purpose of this work is to study the effect of heat fluxes at braking on the value of the implemented friction factor in the tire contact patch with the asphalt-concrete pavement surface at low temperatures. METHODS. The study uses a computational method for obtaining data on the distribution of heat fluxes between the surfaces of pavement and tires when braking with fully locked wheels. RESULTS. The influence of heat fluxes on the implemented friction factor in the contact patch of tires and asphalt concrete pavement surface at negative temperatures is determined by calculation. The calculation methods of heat fluxes in the tire contact area with the asphalt concrete pavement surface at braking is presented. CONCLUSION. It is confirmed that the heat fluxes affect the increase of the implemented friction factor in the contact patch of tires and asphalt concrete surface at negative temperatures.