The PURPOSE of the paper is to develop an operation algorithm of the automatic synchronization system under the restoration of the power supply system after emergency cut-off from the main power source (MPS) and breaking of the power supply system into separate “islands”. METHODS. Some operation stages of the synchronization system use reachability matrices, for the construction of which the Floyd-Warshall algorithm is used. RESULTS AND THEIR DISCUSSION. The operation of the synchronization system using the proposed algorithm is demonstrated on the test scheme of the power supply system. The execution of the algorithm is triggered in case of emergency shutdown of current breakers (CB); the algorithm identifies the structure of the “islands” formed as a result of the accident and forms a definite order of the synchronization process; the error signals determined by the algorithm are applied to automatic speed regulators (ASR) and automatic voltage regulators (AVR) of distributed generators (DG); when the synchronism is achieved the algorithm generates the commands to switch on the current breakers. CONCLUSIONS. The proposed algorithm of the synchronization system allows to reconnect the “islands” formed as a result of the accident between each other and with the main power source. When the power supply system is disconnected from the main power source it is necessary to switch the automatic speed regulators of distributed generators to a floating response to eliminate the frequency deviation from the nominal one. In order to exclude an arbitrary load distribution between the distributed generators when the automatic speed regulators are switched to a floating response it is necessary to use a group control of active and reactive power.

The PURPOSE of the work is conducting of experimental studies of electrical energy quality in an autonomous power supply system of one of the enterprises of the oil and gas production sector on 0.4 kV buses of a 6 / 0.4 kV substation and estimation of the influence of compensating devices on the distribution of higher harmonics in the power supply system with a load having a nonlinear volt-ampere characteristic. METHODS. Numerical analysis of voltage and current distortion degree in the distribution network is performed by instrumental measurement using Resurs-UF2M energy quality analyzer and Hantek DSO 1102B digital oscilloscope. RESULTS AND THEIR DISCUSSION. The study has revealed the exceedance in the permissible values of voltages and current distortion coefficients as well as the dependence of the influence of nonlinear load and reactive power compensation devices on harmonic composition in power system nodes. CONCLUSIONS. The higher harmonics of current and voltage significantly worsen the operating conditions of the main elements of power system equipment having a negative effect on relay protection, automation, telemechanics and communication devices that often results in serious technological failures and significant economic costs given the steady growth in the number and power of nonlinear devices in the electric power industry.

PURPOSE. As the complexity of electric power systems (EPS) constantly increases, the task of ensuring adequate operation of relay protection devices (RP) is becoming more and more relevant. To solve it the authors propose to use the detailed mathematical models of the combination of measuring transformers of relay protection together with modern EPS simulators. The adequate modeling of measuring transformers is very important, in particular, the core magnetization process, since measuring transformers in many respects determine the shape of the controlled signal of relay protection and affect its operation. However, the absence of an accurate mathematical description of the characteristics of measuring transformer core magnetization leads to the use of simplified models which do not reflect all processes in the core. The purpose of the work is development of a mathematical model of hysteresis featuring high reproduction accuracy of transformer core magnetization reversal processes. METHODS. The main research method is mathematical modeling of ferromagnetic material magnetization reversal. The research is performed using the MathCAD software package. RESULTS AND THEIR DISCUSSION. The article presents the fragments of development and study of a mathematical model with a magnetic hysteresis memory based on the Preisach theory, which reproduces both major and minor hysteresis loops with high accuracy. CONCLUSIONS. The analysis of existing mathematical models of current transformers allowed to identify the most promising approach for describing the magnetization process i.e. Preisach theory, which, due to the complexity of its implementation is not used in widely spread software and hardware/software complexes. A mathematical model of a hysteresis with the memory of matter state has been developed on the basis of the Preisach theory for describing the magnetic hysteresis process. The preliminary studies of the model confirmed the correctness of model operation.

The PURPOSE of the paper is to substantiate the best location of wind turbines and evaluate the scale of their rational use for off-grid consumer energy supply in the eastern Arctic zone of the Russian Federation. METHODS. The express method for the selection of an optimal capacity of the renewable energy source for the off-grid consumer is used to provide a rationale of wind farm cost-effectiveness. RESULTS AND THEIR DISCUSSION. Depending on the site location in the Arctic regions three typical groups of annual variation in average wind speeds have been identified. Dependences of the ratio of optimal capacity to the maximum consumer load on the variation of the installed capacity utilization factor have been obtained for different annual wind resource distributions. CONCLUSIONS. The magnitude of the wind potential has the most considerable effect on the value of the optimal capacity of a wind farm as a component of a wind/diesel system, while the influence of the annual distribution is not so pronounced and manifests itself mainly at its low values. The conducted studies allowed to state the priority of using the wind power potential for power supply on the coasts of the northern and eastern seas of the Arctic zone of the Russian Federation. However, when substantiating the cost-effectiveness of wind power plant projects, it is very important to choose its optimum capacity. The latter depends both on the wind power potential indicators and on their annual variations.

PURPOSE. The paper deals with the model of shaping a processed surface in the operation of external cylindrical grinding with a traverse feed performed in an automatic cycle on CNC machines. The developed model of surface formation allows to conduct a step-by-step calculation of the current values of the actual radial in-feed and radii sizes in the different sections of the machined surface and predict the values of grinding surface dimensions throughout the whole grinding cycle for the given processing conditions. METHODS. The basis for the creation of computer-aided design systems serve the data presented in the regulatory literature that makes their use inefficient for the development of cycles for CNC machines. Existing engineering techniques also based on the recommendations of regulatory literature or on particular empirical data do not take into account the changes in variable processing conditions. RESULTS AND THEIR DISCUSSION. The paper discusses the simulation features of grinding cycles along the length of the machined part surface, shows a calculation scheme that establishes the relationship between the graphs of the accumulated software (tп_k,i,z) and actual (tф _k,i,z) feeds, tension (tн _k,i,z), elastic strain (у _k,i,z) of the technological system with the radii of the machined surface (R _k,i,z ) when grinding a non-circular workpiece with the maximum radius (Rзаг_max), original workpiece radii (Rзаг_k) and initial radial run-out, which is calculated by formulas. CONCLUSIONS. Presented in the article formation model of the grinding surface in the operation of external cylindrical grinding with a traverse feed performed on a CNC machine allows to predict the actual dimensions of the machined surface for a given cycle and technological conditions of machining as well as to construct a model of the machined surface.

The PURPOSE of the paper is to develop a transdisciplinary model that provides an integrated solution for interdisciplinary and disciplinary problems as well as creates the conditions for the specialists in different subject areas to participate in their solution. METHODS. Integration of data and knowledge referring to the subject areas significantly different in goals and objectives with the properties of materials and structures needed for the substantiation require the development of methods and models that can reflect the origination and development patterns of phenomena, processes, events and states causing the damage and destruction of structures. One of these models is implemented on the basis of the transdisciplinary approach that allows to formulate the goals and objectives combining the knowledge and data and providing the specialists in various subject areas with the understanding of the desired results and their achievement methods. RESULTS AND THEIR DISCUSSION. A transdisciplinary model reflects a formal (logical) relationship between degradation processes, damages caused by them, limit state criteria and sudden failures. At the same time, a certain set of objectives reflects the interconnected objectives for different development stages of damages and information aspects characterizing functional, technical and physical conditions of the materials and structures produced from them. The model provides the interconnected solutions of many interdisciplinary and disciplinary problems. CONCLUSIONS. The transdisciplinary model has been developed that reflects the interdisciplinary and disciplinary purposes and objectives to justify the properties of materials and structures. The clearness of purposes, objectives and necessary data and knowledge provides effective interaction between the experts and specialists in solving problems.

The PURPOSE of this paper is search for the opportunity to decrease the production accuracy of wheel profile surfaces when the accuracy of transmission with intermediate rolling bodies and a free bracket remains the same to reduce the production cost of critical parts. METHODS. The production accuracy analysis is carried out using the analytical methods of complete and incomplete interchangeability taking into account the features of transmission linkage with intermediate rolling bodies and a free bracket. RESULTS AND THEIR DISCUSSION. When part accuracy decreases without any change in fit combinations the manufacturing clearance in the transmission linkage with intermediate rolling bodies and a free bracket increases as an arithmetic progression (when the accuracy decreases by one accuracy grade the clearance increases at 20µm minimum). It can have a negative effect on transmission operation. At the same time the change in fit combination and decrease in part accuracy results in the reduced manufacturing clearances in the transmission linkage with intermediate rolling bodies and a free bracket. The origination of a limit manufacturing clearance is the most probable under production of parts by upper or lower tolerance deviations of size. When changing fit combinations of mate parts from H7-h6-h7 to H8-h8-k7 it is possible to reduce the maximum manufacturing clearance by 12 µm and limit clearances up to 8 µm. CONCLUSIONS. It is found that it is possible to select the combinations of mate part fits in the transmission with intermediate rolling bodies and a free bracket to reduce their production accuracy on one side and preserve the transmission accuracy not lower than the start production level on the other. The selection of optimal fit combination and accuracies will allow to reduce the production cost of vital parts of transmission with intermediate rolling bodies and a free bracket as well as to increase the competitiveness of these transmissions on the market.

The PURPOSE of the paper is to perform a comparative analysis of the measurement results of residual stresses in steel 13Х15Н4АМ3 (VNS-5) after longitudinal turning with a varied feed. The work has the following objectives: to determine the influence of processing modes at longitudinal turning on technological residual stresses formed in a sample and to compare the methods different in principle for the study of the stress-strain state of material on the part surface. METHODS. The study uses a mechanical method for determining residual stresses and an X-ray diffraction analysis (XRD). Being the most widespread in the analysis of residual stresses in metal samples, these methods feature satisfactory accuracy, convergence of results and are widely applied both for research and production purposes. RESULTS AND THEIR DISCUSSION. A brief description is given to the production process of samples used for residual stress research by the mechanical method using UDION-2 research equipment. The diagrams of residual stress distribution in the surface layer of samples after longitudinal turning with a varied feed are obtained. The measurement results received through the use of the mechanical method and XRD analysis on sample surface are compared. Consideration is given to the features of methods and equipment for the study of technological residual stresses, which includes the UDION-2 research equipment for residual stress measurement by the mechanical method and the XRD XStress 3000 G3R diffractometer. CONCLUSIONS. The growth of the feed is accompanied by the increase in the depth of the minimum residual stresses, the depth of the active area of residual stress diagrams and the decrease in the value of the tangential stress τ_zx0 on the surface. A sufficiently high convergence of the measurement results of residual stresses on the sample surface by the mechanical method and X-ray diffraction analysis is found.

PURPOSE. The anodic behavior of indium doped AB1 alloy is studied in the NaCl electrolyte medium in the region of indium concentration up to 0.5 wt % by a potentiostatic method. The doped alloys are demonstrated to have a more satisfactory corrosion resistance than the initial alloy AB1. METHODS. The studies are performed in the NaCl electrolyte medium using the PI-50-1.1 potentiostat. RESULTS AND THEIR DISCUSSION. Indium additions reduce the corrosion rate of AB1 alloy by 75% in the investigated media. When the indium concentration increases up to 0.5 wt % the corrosion rate of AB1 alloy decreases monotonically. It is shown that the improved corrosion resistance of AB1 alloy when doped with indium is explained by its modifying effect on the structure of the eutectic aluminum-beryllium alloy AB1, as well as by increasing the true surface of the anode or by compacting the protective phase layer of oxides with poorly soluble oxidation products. CONCLUSIONS. The conducted studies show that doping of the aluminum-beryllium alloy of eutectic composition (AB1) with indium improves its corrosion resistance, which is accompanied by a shift of the alloy free corrosion potential in the positive region.

PURPOSE. The main component of fire-resistant bricks is clay. In particular, fire-resistant bricks are used for lining of pouring ladles and smelting furnaces. A technological indicator of clay suspension is viscosity. The paper studies the influence of concentration of various Kazakhstan deposits clays on suspension viscosity. METHODS. The experiments on viscosity determination were carried out using the SV-1A Viscometer. RESULTS AND THEIR DISCUSSION. Clay in refractory mix is present as a binding agent, therefore, it should be evenly distributed throughout the whole volume of the mix. At the same time, viscosity has a strong effect on coating adhesion and cohesion that finally affects the efficiency and durability of the coating. In broad terms the shape and size of clay particles as well as the quality of the present liquid affect the viscosity. The diagrams of viscosity variation have shown that the suspension with the clay from the Beloe Glinishche field has the smallest viscosity, the greatest viscosity has the suspension with the clay from the Darat field. It has been determined that the clay particles of the Beloe Glinishche field have a cylindrical form, the clay particles of the Darat field are granular, whereas the clay particles of the Fedorovskoe field are flake-like. The clay from the Beloe Glinishche field in combination with the finely ground fire-clay in the proportion of 60:25 is considered to be the most useful for binding. This contributes to the production of fire-resistant bricks with the optimum evenly distributed sealed porosity (10-15%) that raises the service life of a fire-resistant composition. CONCLUSIONS. The conducted studies have shown that the greatest viscosity has the suspension based on Beloe Glinishche clay when the proportion of clay to chamotte is 50:35. The suspensions based on Beloe Glinishche clay and Fedorovskoe field clay feature similar viscosity when the proportion is 60:25. The tests of the proposed refractory mix carried out when pouring steel in the foundry shop of the Factory named after Parkhomenko LLP (Karaganda) have shown the increase in the service life of lining by 20% as compared with the composition based on the bentonite clay used earlier.

PURPOSE. Formation of elemental sulfur under sulfide concentrate pressure leaching leads to the emergence of sulfur-sulfide granules which significantly reduce the rate of zinc dissolution. This problem can be solved through the application of surfactants preventing the negative effect of molten sulfur, and allowing to avoid granule formation under leaching. Lignosulfonates (woodworking industry waste) are the surfactants most widely used for sulfide concentrate pressure leaching. This paper studies the effect of the additives of anionic surfactants and their mixtures with lignosulfonate on the surface tension of aqueous solutions, zinc extraction and grain size distribution of cakes after sulfide zinc concentrate pressure leaching. METHODS. Surface tension of aqueous solutions was determied by a stalagmometric method. Leaching was performed in a titanium autoclave in the presence of lignosulfonate, sodium dodecyl benzene sulfonate and sodium dodecyl sulfate. After leaching the solutions were analyzed on zinc content using an atomic absorption spectroscopy. Grain size analysis of cakes was carried out by a laser diffraction particle size analyzer. RESULTS. The work has shown a synergetic influence of anionic surfactants and lignosulfonate on the decrease of aqueous solution surface tension. The greatest effect has the mixture of lignosulfonate and dodecyl benzene sulfonate (LS-DBS), namely in the range of sodium dodecyl benzene sulfonate (SDBS) concentrations of 400-600 mg/dm³. The use of composite surfactants has allowed to obtain high indices of zinc extraction and optimal particle size of cakes after leaching. When lignosulfonate (LS) and SDBS are used in combination the extraction of zinc increases from 77.2% up to 82.8%, whereas the bulk of the cake (96.7%) has a particle size of -150 μm. CONCLUSION. The composite surfactants (lignosulfonate and sodium dodecyl benzene sulfonate) can be recommended for use at pressure leaching of sulfide zinc concentrates.

The PURPOSE of the paper is to study the chemical composition of the research object represented by the refractory part of the spent lining (SL) of aluminum electrolysers and to investigate the process of fluorine recovery from the spent lining refractory part by a hydro-metallurgical method. The study is also given to the influence of aqueous leaching parameters (duration and temperature) on the fluorine recovery into solution and the evaluation of the thermodynamic probability of reactions between the lining components and various solvents under leaching. METHODS. The methods of x-ray fluorescence and x-ray phase analysis as well as scanning electron microscopy are used to study the composition of samples. The liquid analyzer EXPERT-001 with a combined pH electrode ESK-10601/7 K80.7 and an ion selective electrode ELITE-221 of Nika company are used to measure the pH and concentration of water-soluble forms of fluorides. RESULTS. The chemical composition of the research object has been studied. The influence of process temperature and duration on fluorine recovery from the spent lining under water-soluble NaF dissolution has been investigated. The thermodynamic calculations of interaction reactions of the main fluorine-containing components of lining such as cryolite Na₃AlF₆, chiolite Na₅Al₃F₁₄, calcium fluoride CaF₂ with the solutions of sodium hydroxide, carbonate and hydro-carbonate under leaching have been performed. CONCLUSION. Conducted laboratory studies allowed to determine that the maximum fluorine recovery of 62.95% is achieved under water leaching at the temperature of 60°C and process duration of 120 minutes. Based on thermodynamic calculations and performed experiments a basic technological scheme is proposed for regenerative cryolite production from leaching solutions using either the solutions of sodium bicarbonate or the solutions of gas purification and slime waters of operating plants of primary aluminum production.

PURPOSE. Today the search for and development of an effective and environmentally-friendly processing technology of refractory gold-arsenic flotation concentrate is a relevant technological task in the field of gold metallurgy. The purpose of the study is conducting of experiments on pressure oxidation of gold-arsenic flotation concentrate of Ikkijelon deposit (Republic of Tajikistan), recovery of precious metals from pressure oxidation products by cyanidation as well as the study of the material composition of pressure oxidation products. METHODS. The material composition of pressure oxidation products has been studied using optical emission, atomic absorption, X-ray diffraction, gravimetric, titrimetric, photometric, IR-spectroscopic, diffractometric, quantitative mineralogical methods, and a microscopic analysis. The content of gold and silver in the sample and in the derived products has been determined by the method of direct assay analysis. RESULTS AND THEIR DISCUSSION. The cyanidation of the initial product provides 55.1% and 75.8% recovery of gold and silver respectively. In addition to low gold recovery the processing of initial concentrate is characterized by a relatively high consumption of dissolver (sodium cyanide) and the complexity of formed tailing neutralization from arsenic compounds. The studies conducted by the authors according to the technology “pressure oxidation - cyanidation” have shown the 42.03% growth in gold recovery as compared to the cyanidation of the initial concentrate. CONCLUSION. Gold recovery from the refractory gold-arsenic flotation concentrate of Ikkijelon deposit by pressure oxidation allows to obtain high recovery of gold in the post-cyanidation. Based on the obtained results the authors plan to conduct the experiments on pressure oxidation in the presence of halogen-containing reagents in the oxidation process in order to reduce the formation of argentoarosites and to increase the degree of silver recovery under cyanidation.

PURPOSE. The article considers the possibility of applying the author's methods of non-numerical constraint propagation to the problem of qualitative modeling of static and dynamic systems. The general feature for the models of static and dynamical systems considered in this work is that it is intended to use only variables with finite domains for the description of the state of the system. Another feature of the systems under study is that their states may contain underdetermined parameters: the value of a variable can be either completely not determined and be set as a whole domain, or be completely determined and represent a one-element subset of the domain, or be underdetermined, i.e. be set in a kind of some subset of the domain. Formalization of such state description is carried out with the help of vectors, where the components are represented rather by some subsets of the truth sets of the variables than by corresponding single values. Another feature of the models under consideration is the need to co-process quantitative and qualitative constraints (dependences) of the subject domain. METHODS. The proposed methods are based on the representation of qualitative dependences (constraints) of the subject domain in the form of specialized matrix-like structures ( C and D -systems), the use of which allows to accelerate the traditional algorithms of non-numerical constraint satisfaction and expand the scope of such algorithm use. RESULTS AND THEIR DISCUSSION. A special effect from the use of original methods can be expected in poorly formalized subject domains. When modeling poorly formalized subject domains it is proposed to co-process qualitative constraints over the finite domains and quantitative constraints within the framework of constraint programming technology. The proposed methods are iterative and allow to reduce some instances of CSP tasks to smaller-dimensional problems without branching with the analysis of the specific features of the proposed matrix-like structures. CONCLUSIONS. The use of author's methods of non-numeric constraint propagation allows to fill up the range of the problems solved with the help of the mentioned technology with such tasks as inference in production systems with underdetermined parameters, implementation of reasoning in dynamic intelligent systems, structural synthesis of the systems at the initial stages of design works, formation of university curricula and etc.

The PURPOSE of the study is to show the application possibility of the spike (pulse) model of a neuron in automatic control systems with a pulse-width modulation controller that has an artificial neural network in its composition. METHODS. The use of this type regulators makes us solve the problem of parametric optimization that is understood as the determination of the optimal tuning (training) of the synaptic weights of an artificial neural network according to the chosen criterion. Therefore, the neural network training algorithm formed on the basis of the Nelder-Meade method is used in the article. RESULTS. The study has shown that the model of a generalized neuron element provides the lowest values of the integral quadratic criterion under the binary coding of information. CONCLUSIONS. Spiking neural networks can be used in control systems with pulse-width modulation.

PURPOSE. The paper deals with the increase in reproduction accuracy of time and frequency units through the use of predictive autoregressive-moving average models (ARMA)). The methodology of ARMA model creation existing now is based on interactive procedures. This requires highly qualified specialists and prevents the algorithms of optimum filtration from the introduction in the practical activities of time services. METHODS. The study employs the methods of time series analysis, ARMA model construction and the conjugate gradients method. RESULTS. An approach allowing a complete formalization of the procedure of model construction is introduced. A program module implementing the automatic construction of the predicting models that describe the processes of hydrogen standards frequency variation is developed. It is tested experimentally and the results of the work confirming the adequacy of the obtained models are presented. CONCLUSIONS. The formalized methodology of ARMA models construction proposed by the authors will allow to solve the problem of full automation of time series model construction by empirical data and to lower the reproduction error of time and frequency units by group standards up to 30%.The conducted study provides all the reasons to suppose that the developed software module can serve as a basis for creating a standard software for the subsystem of internal comparisons of time and frequency standards in order to be introduced into the experimental operation mode.

PURPOSE. The article presents the procedure, experimental study results, and calculated experimental universal dependence obtained for calculating the radial stiffness of an inclined wheel. METHODS. An experimental technique has been developed to determine the radial stiffness of an inclined wheel tire. The authors carried out the experiments using a device specially designed at the Department of Vehicle Technical Operation and Repair of the Volgograd State Technical University. RESULTS AND THEIR DISCUSSION. A correction factor has been obtained to recalculate the radial stiffness of a vertical wheel to the radial stiffness of the inclined wheel at any value of the inclination angle α. These researches provide the data on the variation of the factor of tire radial stiffness depending on its inclination angle and can be used for the selection of vehicle chassis parameters in order to improve its controllability and stability. CONCLUSIONS. It has been determined that when the wheel is inclined regardless of the direction of inclination within the permissible values for tire operating conditions and preserving its wear resistance (up to 5⁰), the factor of radial stiffness of the tire decreases up to 20%. The study has resulted in obtaining a correction factor for recalculating the radial stiffness of the vertical wheel into the radial stiffness of the inclined wheel at any value of its inclination angle α. The obtained new knowledge about the value of the tire radial stiffness allows more accurate modeling of vehicle stability and controllability.

PURPOSE. The paper presents the results of studies dealing with the determination of the degree of traffic flow impact on the environmental situation in the near trunk road areas of the city of Omsk. METHODS. The study conducted in accordance with the methodology presented in GOST R 56162-2014 allows to calculate the amount of pollutant emissions from a moving traffic flow. RESULTS AND THEIR DISCUSSION. The graphically represented study results reflect the amount of atmospheric emissions of carbon monoxide (CO) and nitrogen oxides (NO_x) over the time interval of 20 minutes on 500 m long sections of Omsk main roads. CONCLUSIONS. Traffic flow driving regimes can be significantly influenced by: the technical means of traffic regulation, location of street pedestrian crossings, location of public transport stops, street parking places and availability of areas intended for maneuvering (turn and U-turn). Besides, the authors make a suggestion on the possibility to add the current methodology by the values of extra emissions of pollutants that take into account the traffic flow driving regimes on the sections of the main urban roads (acceleration, braking, idle running).

PURPOSE. The paper deals with the problem of improving the quality of transport services through the improvement of the structure of the urban public transport rolling stock fleet taking into account the mutual influence of routes. METHODS. To improve the quality of passenger transportation a mathematical model for urban passenger traffic program calculation is formulated based on the criterion of the minimum coefficient of dynamic utilization of the rolling stock capacity and certain restrictions of transport process parameters. RESULTS. An algorithm has been developed for the numerical solution of the problem by means of a directed enumeration of possibilities. The article describes the software of the proposed algorithm which allows to calculate the optimal structure of the rolling stock fleet of public passenger transport providing the maximum quality level of passenger transportation corresponding to the specified passenger tariff. CONCLUSIONS. Having considered the testing results of the effectiveness of the proposed mathematical model, problem solving algorithm and software on the route network of the Krasnoyarsk city, it was determined that the calculated transportation program significantly improves the quality of transport services and efficiency of urban passenger transport in the city of Krasnoyarsk. The network's average dynamic capacity utilization ratio has decreased from 0.3 to 0.23 while ensuring the cost-effective operation of transport organizations that service the routes. The proposed program excludes the overpacking of the rolling stock, while in the initial program the proportion of the routes served with the exceeded capacity of rolling stock reached 60%. The transportation capacity of the rolling stock fleet has increased by 10% due to the higher proportion of larger capacity buses. The traffic intensity in the busiest sections of the network has been reduced by 66%, which favorably affected the road traffic. Therefore, the developed mathematical model and the algorithm for calculating the program of urban passenger transportation based on a directional enumeration of possibilities under certain restrictions on the parameters of the transport process, allows to calculate the optimal structure of the rolling stock fleet with regard to the mutual influence of routes.