PURPOSE. The use of renewable generation sources causes bidirectional power flows and overvoltages in low voltage distribution networks. The information on the current values of all mode variables, which is necessary for the efficient monitoring and control of the distribution network can be obtained through the processing of measurements from the smart meters. The paper proposes a new approach to the solution of the state estimation problem of a three phase distribution network based on the measurements of voltage modules and nodal powers or currents. METHODS. It is proposed to solve the nonlinear state estimation problem on the basis of nodal power and voltage measurements instead of Newton’s method traditionally used for this purpose. The quadratic function of residuals at each simple iteration and at linear state estimation based on the measurements of nodal currents and voltages is minimized by the weighted least squares method with or without constraints on zero currents at the transit nodes or by the Hachtel matrix method. RESULTS AND THEIR DISCUSSION. The effectiveness of the proposed methods is illustrated using linear and nonlinear state estimation for each hour of the daily curve of nodal power variations for the three phase 32 node low voltage test network. CONCLUSIONS. Application of the simple iteration method for nonlinear state estimation makes this procedure as trivial as the procedure of linear state estimation. The Hachtel matrix method allows to obtain the minimum value of the objective function compared to the value of the objective function for the weighted least squares method with and without constraints.

PURPOSE. The paper presents the model of the DC/DC matching (controlling) converter built from the elements of the SimPowerSystems MATLAB/Simulink library, the study of dynamic properties and the methods to control the DC/DC converter. METHODS. The set purpose is achieved through the use of the modeling methods of the mode of step-down/up output voltage of the converter with two power switches, which allows significant improvement of operating performance as compared with buck - boost converters based on a single power switch, as well as with traditional converters with two power switches. RESULTS. A model and design of the DC/DC converter with two power switches is proposed as well as the control method of the DC/DC converter on a computer model. The converter under consideration has the characteristics of a buck - boost transformer. CONCLUSIONS. Having studied the dynamic properties, we found the methods to control a DC/DC converter on a computer model. The development of a matching energy converter and its control principles allowed to stabilize the battery capacity that resulted in improved possibility of maneuvering ships, submersibles (bathyscaphes, unmanned deep-submergence vehicles, etc.).

The PURPOSE of the paper is to formulate the criteria for a simplified technical and economic evaluation of backbone electrical network development variants. METHOD. The approach is based on the technical and economic evaluation of variants. RESULTS. The criteria for the simplified technical and economic evaluation of development variants for the backbone electrical network have been formulated. The variants have been calculated by blocks including capital investment, annual power losses, annual costs, discounted costs, areas of alienated land, aluminum consumption for wires. The calculation of the enumerated indices is envisaged for an option as a whole and for individual network components such as overhead AC transmission lines, electrical AC substations, shunt reactors, reactive power sources, overhead DC transmission lines, transformer substations. CONCLUSIONS. The elaborated system of criteria has been tested in practice and can be applied to perform a simplified technical and economic evaluation of backbone electrical network development variants and determine system efficiency of the new types of power transmission.

The PURPOSE of the paper is to develop a method of electric circuit steady state response calculation (ECSSR) using a genetic algorithm (GA). METHODS. A method is proposed for ECSSR calculation using genetic algorithms. RESULTS. We have shown the possibility in principle to use a genetic algorithm for ECSSR calculation. An algorithm and a program for ECSSR calculation by the genetic algorithm method have been developed. The calculation results obtained through the use of the genetic algorithm method have been verified by the calculation results received with the use of traditional iterative methods of mathematical analysis. CONCLUSION. An alternative method of ECSSR calculation has been developed. Its advantage is high calculation accuracy under significantly reduced requirements for computing resources.

The article deals with the issues of standardization in the field of reliability of engineering facilities and systems. The paper considers both general standardization problems in Russia and those that arose in the development of the interstate standards GOST 27.002-2015 “Reliability in engineering. Terms and definitions” and GOST 18322-2016 “Mechanical material maintenance and repair system. Terms and definitions”. The emphasis is placed on the harmonization of these standards with the international standard IEC 60050-192. Dissimilarity of standards is the result of different approaches to reliability provision, methods and technologies of equipment maintenance and repair in Russia and abroad. The issues of their coordination with current national and interstate standards, as well as with other terminological and reference documents are discussed. METHODS. The standards have been developed in accordance with the program of works on interstate standardization on the basis of current standards, rules, regulations and recommendations on standardization subject to the up-to-date advances in science and technology. RESULTS AND THEIR DISCUSSION. The developed standards GOST 27.002-2015 and GOST 18322-2016 meet modern reliability requirements, take into account the domestic experience in terminology standardization in the series of national standards GOST 27.002 and are harmonized with the international standard IEC 60050-192. The standards are based on the current principles of reliable equipment maintenance and repair technology provision that are adopted in Russia and abroad. Having been considered in Federal Agency for Technical Regulation and Metrology and publicly discussed, the standards were adopted by the Interstate Council on Standardization, Metrology and Certification and came into operation. CONCLUSIONS. The analysis of the current standards on reliability, maintenance and repair of equipment has shown that the state of the fund of interstate standards in this area requires modernization and improvement. However, the process of standard reformation in the context of Russian economy transition to market relations should be in tune with the changes occurring in the corresponding spheres and meet the international requirements. Special attention should be paid to the harmonization of national and interstate standards with international ones in order to ensure the semantic match of terms considering differences in techniques and technologies in Russia and abroad. GOST 27.002-2015 and GOST 18322-2016 are developed in accordance with modern requirements for standardization and are harmonized with the international reliability standard IEC 60050-192. GOST 27.002-2015 Dependability in technics. Terms and definitions. En-acted 1 March 2017 / G.N. Cherkesov, V.A. Netes, V.L. Shper, Yu.I. Tarasiev, G.F. Kovalev, G.A. Fedotova, I.N. Dolgopolov, I.B. Shubinsky, A.V. Baturin. Moscow: Standartinform, 2016. GOST 18322-2016. Maintenance and repair system of engineering. Terms and definitions. Inacted 1 September 2017 / N.I. Voropai, G.F. Kovalev, G.A. Fedotova, I.A. Sher. Moscow: Standartinform, 2017. IEC 60050-192: 2015. International electrotechnical vocabulary - Part192: Dependability. М.: International Electrotechnical Commission (IEC). 2015.

The PURPOSE of the paper is to determine the influence patterns of the parameters of surface machining (cutting speed, tool feed and deformation) by polymer abrasive wheels on the roughness of the machined surface and develop a mathematical model of microrelief formation of this surface. METHODS. The study involves analytical and experimental methods using the wheels of the company 3M (Minnesota Mining and Manufacturing Company) of the brands Scotch-Brite™ FS-WL, DB-WL, CF-FB of different coarseness. RESULTS AND THEIR DISCUSSION. We have developed a mathematical model of roughness formation based on the interaction of an elastic abrasive wheel cutting microrelief and a machined surface. Abrasive grains are introduced into the machined material under cutting microrelief interaction with the processed surface. The average depth of grain introduction has been determined by the set mechanical properties of the machined material and the vertical component of the cutting force taking into account lapping and elastic recovery of scratches. This depth is represented by the height of the machined surface roughness. Experimental check of the cutting speed and feed on the samples made of V95pchT2 alloy at various deformations of a wheel has shown close agreement of experimental and theoretical results. CONCLUSION. The developed theory of part surface microgeometry formation allows analytical determination of roughness by the known parameters of the tool depending on the processing modes. Having optimized the technological process, this mathematical model can be used as a restricting function for the achievement of the set optimization criterion, for example, the criterion of target economic function.

Shot peen forming (SPF) is used for forming panels and skins as well as for hardening. As a rule, shot peen forming is performed after milling. The surface roughness obtained as a result of sequential performance of these operations is a complex structure, a combination of an original microrelief and shot peening indentations of different depths and chaotic distribution along the surface. As far as shot peen forming is a random process, the surface roughness resulting from milling and shot-blasing is random too. The PURPOSE of the paper is development of a mathematical dependence model of arithmetic mean deviation of surface roughness profile under shot peen forming. METHOD. A technique is proposed for calculating surface roughness after shot peen forming based on the indentation depth analysis. RESULTS. The analysis of depths and distribution of shot peen indentations along the surface allowed to identify the shift of the original profile center plane and build a mathematical model of the arithmetic mean deviation of the profile surface. Experimental testing proved model validity and determined the inversely proportional dependency of the basic area on the coverage degree.

The PURPOSE of the paper is to determine the temperature ranges of dehydration and phase transformation of the initial components of the mixture of TiО₂-B₂О₃-C - sucrose, hydrated titanium and boron oxides under different conditions of titanium diboride synthesis. METHODS. The method used in the study is thermal analysis of the reaction mixture on the STA 429CD (NETZSCH) synchronous thermal analysis unit using a platinum-platinum-rhodium holder for “TG + DSC” type samples in helium, argon, vacuum and air atmospheres. RESULTS AND THEIR DISCUSSION. Boric acid is transformed in three stages at the temperature range of 73 ÷ 450°C: at the first stage the removal of 1 mole of water causes the transformation of the orthoboric acid H₂TiO₃ into the metaboric HBO₂ , which is transformed into boric anhydride В₂О₃ with further evaporation of moisture. The third stage features complete removal of moisture under the melting of boron oxide in the temperature range of 300 ÷ 600°C. The fluorine-doped titanium oxide TiO(OH)_2-xF_x loses moisture in the temperature range of 65-130°C, but its amorphous form TiO_2-xF_x undergoes its first phase transition to the crystal anatase modification of а-TiO₂ only after heating above 700°C. The greatest transformation and reduction depth of titanium oxide occur when the reaction mixture is heated in the air atmosphere. Pyrolysis of sucrose C₁₂H₂₂O₁₁ to complete removal of moisture and release of active carbon is a predominating process in a wide temperature range of 350÷740°C. CONCLUSIONS. Based on the thermal analysis results of the samples of the initial reaction composition under different atmospheric conditions the temperature ranges of the dehydration and transformation processes of mixture components have been determined. Found regularities must be accounted and applied under the low-temperature synthesis of titanium diboride TiB₂

The PURPOSE of the paper is to analyze the adequacy of existing mathematical models of coke quality control by M₂₅ and M₁₀ parameters based on both their internal logic and the theory and practice of coking; to select and justify the model recommended by the authors for coke quality control in the blast-furnace process. METHODS. The models are analyzed using the method of elementary algebraic transformations in order to demonstrate the linearity of the mathematical model equation, compare accepted axiomatic positions adopted in the models with the theory and practice of coking, and compare the predictive capabilities of the mathematical models for their adequacy recognition. RESULTS AND THEIR DISCUSSION. A mathematical generality has been determined between the coefficients K_opt and K_{opt (Vt)} , which were previously proposed by different authors for predicting coke quality parameters M₂₅ and M₁₀. General formulas have been proposed for constructing the coefficients of K_opt and K_{opt (Vt)} type. General formulas have been given for constructing the reduced mathematical models built on the basis of K_opt and K_{opt (Vt)} type coefficients. The models built on the basis of K_opt and K_{opt (Vt)} coefficients have been compared with the models used at various coke-chemical enterprises of Russia. Consideration is given to the predictive abilities of adaptive and neural network models. The adaptive model has a better predicting capacity as compared with other models. The neural network model has insufficient forecast precision of coke quality based on GOST 54250 verification. CONCLUSIONS. It is recommended to use an adaptive model to control coke quality by М₂₅ and М₁₀ parameters in a blast-furnace process but it is useless for the optimization aimed at reducing the cost of coke. The inexpediency of construction and use of the models based on the coefficients K_opt and K_{opt (Vt)} is expressed. The authors suppose that the model built on the basis of artificial neural networks is promising in terms of coke quality control by М₂₅ and М₁₀ parameters but it is poorly studied.

PURPOSE. Today the development of an efficient technology of refractory ore processing is quite problematic, therefore the achievement of high degree of gold recovery is a relevant problem. The purpose of the research includes investigation of mineral and chemical composition of the gold-bearing ore of the Taror deposit, performance of the series of tests on ultrafine grinding (UFG) of ore prior to cyanidation and pulp processing after UFG by the method of atmospheric oxidation followed by cyanidation, study of the ground particle size effect on the degree of Au recovery under conventional cyanidation and search for an alternative technology of gold recovery from refractory gold-bearing ores. METHODS. Diffractometric and quantitative methods are applied to analyze the mineralogical composition of the ore. Optical emission, atomic absorption, phase, IR-spectroscopic, gravimetric, titrimetric and photometric methods are used to study the chemical composition of the sample. Gold and silver contents are defined using direct fire assays. RESULTS AND THEIR DISCUSSION. The obtained results have shown that the Taror ores refer to refractory ore type. It means that traditional cyanidation method without application of any additional process operations fails to present any acceptable results on gold recovery. Application of the UFG method followed by atmospheric oxidation has increased gold recovery by 7.33% for this type of ore. CONCLUSION. Application of UFG followed by atmospheric oxidation enables efficient processing of refractory ores, which was considered earlier economically unviable. It is planned to study this type of ore further by flotation concentration methods, carry out a series of tests on flotation concentrate UFG and atmospheric oxidation of ultrafine ground pulp with the following cyanidation in the sorption mode.

The PURPOSE of this work is to discuss the methods of production-economic system operation quality assessment on example of one of the stations of the Ulan Bator railway. METHODS. The methodology is based on the developed ontology of the station transformed into a production knowledge base of a special type. Every product has truth value specified by experts on a scale [0,1]. It is considered as a relative value component of the system. The assessment procedure is represented in the form of a dialogue with the expert system into which functional element state estimations are introduced. As a result an aggregate assessment is derived in the form of a number within the interval [0,1] that measures the truth value of the assertion on system functionality. RESULTS. The study has resulted in the development of fuzzy inference-based aggregate estimation of a production and economic system involving the technology of expert systems. CONCLUSIONS. The methodology can be applied for estimation aggregation in various object domains.

PURPOSE. The paper presents a mathematical model of the passenger flow entering a transfer hub as well as a simulating model and a software complex implementing it. METHODS. The mathematical model is based on the author's approach, which uses the theory of BMAP-flows. The advantage of BMAP is the possibility of a single description of several incoming request flows (both correlated and independent) while maintaining their structure. RESULTS AND THEIR DISCUSSION. The characteristics of individual passenger flows have been determined and their general model has been built for the current transfer hub "Vladykino" in Moscow. An algorithm for BMAP flows generation has been proposed and a model experiment has been performed. The parameters of the BMAP flow have been determined considering the required correspondence of the simulated value of the total incoming passenger traffic and the volume of passengers in the Vladykino transfer hub in rush hours in 2025. CONCLUSIONS. The obtained results will find application in the general assessment of transfer hub operation efficiency, maximum permissible load and identification of "bottlenecks" in the structure of the passenger terminal.

PURPOSE. The paper provides the analysis of tools and methods of new expert system development using expert system shells. METHODS. The operation process of automated control systems of process plants requires constant estimation of the values of various parameters. It is often when these parameter values can not be obtained by traditional methods involving direct measurement or calculation by known analytical dependencies. This situation is especially typical for the systems with a high level of uncertainty which do not have a sufficient past history of operation. Heuristic methods based on the assessments of experts in the relevant field are appropriate in this case. RESULTS AND THEIR DISCUSSION. The obtained results of the study have allowed to systematize the knowledge on the application of the development methods of new expert systems using expert system (ES) shells which take into account the features of different programming tools and provide higher efficiency through the exhaustive search for more alternatives when choosing a solution. CONCLUSIONS. Based on the high-quality experience of a group of specialists the development methods using ES shells analyze the effect of a larger volume of new factors through their evaluation under the construction of strategies and addition of prediction capabilities.

The PURPOSE of the paper is search for new and modernization of known methods for generating random processes with given static (probability distribution law) and dynamic (correlation and structure functions) probabilistic properties. METHODS. The main research methods are the methods of probability theory, mathematical statistics and numerical methods. RESULTS. The object of the study is a permutation technology for generating random processes with simultaneously set probability distribution law and autocorrelation function. This technology is simple in software implementation, has high speed and allows to enter required probability properties with the accuracy of their reflection sufficient for engineering application (for example, in simulation modeling). The Bernoulli (binary) law has been taken as a law of generated process probability distribution. The characteristics reflecting probabilistic dependencies in generated implementations of random processes have been considered. The structural functions of the binary process generated by a permutation procedure have been studied. CONCLUSION. The conducted research allowed to expand the possibilities of probabilistic dependency estimation due to the use of structural functions. This dependency estimation tool has broader indicative properties as it is able to identify random processes with stationary increments.

RELEVANCE. Pulpchip hoppers are ones of the most important installations in pulp and paper production (PPP) equipment. The effective use of the hopper is the condition of effective operation of the entire production. The main parameter in the design of the hopper is its discharge rate, which depends on many parameters and, first of all, on humidity and bulk density. However, this issue has not been sufficiently studied due to the lack of sufficiently correct research methods of the process. The latter is a serious handicap to the improvement of pulp and paper technologies. The PURPOSE of the paper is to obtain a functional dependence of the pulpchip discharge rate from the hopper depending on the parameters of chip moisture and bulk density on the basis of a fuzzy inference. METHODS. Due to the fact that input data are uncertain, insufficient, inaccurate and indeterminate we have used fuzzy modeling as a tool of the theory of fuzzy sets. RESULTS. We have performed the procedures of fuzzy modeling problem description, reduction to fuzziness and development of the rule base for fuzzy products. The Fuzzy Logic Toolbox of the Matlab application has been used to synthesize the fuzzy model of the resulting dependence of the pulpchip discharge rate from the hopper on the parameters of pulp humidity and bulk density. CONCLUSIONS. The proposed fuzzy inference-based function of chip discharge rate takes into account the main technological parameters of humidity and density; comparison of simulation results with experimental data shows sufficient adequacy of the developed model and allow to recommend it to be used in the design practice of pulp and paper production equipment.

The PURPOSE of the article is to develop the program software for solving the parametric estimation problem of the models of stochastic linear discrete systems in the presence of outliers in measurement data based on Särkkä - Nummenmaa and Izanloo - Fakoorian - Yazdi - Simon filters as well as to study robust procedures of parameter estimation in order to identify the most effective of them. METHODS. A quasi-likelihood estimation method is used in the study. RESULTS AND THEIR DISCUSSION. As exemplifies the model of a DC motor control system with different location of outliers, the problem of unknown parameter estimation cannot be solved without the use of robust filter. The application of the robust filters allows to improve the estimation quality by at least 1.8% under random location of outliers and by 6.81% under the grouped one. CONCLUSIONS. It is found that the robust estimation procedure based on the Izanloo - Fakoorian - Yazdi - Simon filter provides the most accurate parameter estimates.

PURPOSE. The work deals with the justification of the proposed by the authors aerodynamic configuration of the carrying system of the wing-in-ground-effect (WIG) craft and the study of its aerodynamic characteristics. METHODS. Based on the analysis of known ground effect vehicle aerodynamic configurations and their features the authors propose an original aerodynamic configuration of the WIG craft carrying system. Aerodynamic studies are performed on the basis of a computational experiment using the ANSYS software package. The article presents the formulation of the problem, boundary conditions and the features of building a mathematical model of carrying system flow in ANSYS with the justification of the selected approaches. RESULTS AND THEIR DISCUSSION. The article presents some results of studying aerodynamic characteristics of the WIG craft using the proposed carrying system. The aerodynamic characteristics of the proposed configuration, their dependence on the main flight parameters such as the angle of attack and the altitude of flight, the possibility to control their values by the deflection of control surfaces are assessed on the basis of the obtained data. Consideration is also given to the features of flow around the carrying system that ensure its high load-carrying properties and continuous flow around at significant carrying surface angles against the incoming flow. The presented results allow to evaluate the possibilities to implement design tasks which serve the basis for the target to form the proposed aerodynamic configuration of the carrying system. CONCLUSIONS. The proposed aerodynamic configuration provides a wide range of WIG flight operation speeds as well as the possibility to fly at sufficiently low speeds. The low speeds of WIG horizontal flight allow to reduce the transition speed to the flight mode at taking-off and to the mode of static air cushion and aquaplaning at landing, which enables maneuvering with smaller turning radii in the horizontal plane when flying on the route.

PURPOSE. Among many retail facilities located in cities and suburbanized territories supermarkets are the most problematic objects today in terms of transport load as transport and pedestrian flows they generate are larger than those to pharmacies, specialized stores, offices and services. Two indisputable factors including availability and the widest range determine persistently high demand of supermarkets. Therefore, significant visitor flows supermarkets generate rapidly bring the capacity of the adjacent road network and nearby parking lots to the end of their resources. The facts above determine the purpose of research, which is to identify the daily trip generation, as well as the associated characteristics of the operation of the objects of attraction reflecting the mode of movement, vehicle occupancy, peak activity of visitor arrival, number of parked vehicles on an example of the supermarkets in the city of Irkutsk. METHODS. The feature of the study is the survey of supermarkets under investigation during the daily period of their operation. It should be noted that their location, distance from the main street and the city center, their area and availability of parking spaces were different. RESULTS. The estimation of transport demand to these retail facilities showed that remoteness from the main street and city center as well as the availability of parking spaces have the greatest influence on the number of correspondences. CONCLUSION. Having processed the obtained data, it was found that the main activity peak for the supermarkets in question falls upon the arrival of visitors within the interval from 3:00 pm to 8:00 pm. After 8:00 pm the number of visitors turns down.

The Purpose of the study is to ensure the convergence of the rail bar mathematical model and its physical model through the comparison of their amplitude-frequency characteristics in order to study a new method of tensile stress determination. The METHODS used in the study include comparison of the resonant frequencies of the results of physical and mathematical modeling. RESULTS. Having compared the results of physical and mathematical modeling, we obtained the values of resonance frequency deviations for the physical and mathematical models by the finite element method (FEM). CONCLUSIONS. The obtained convergence of the results of physical and mathematical FEM simulation of the track will allow further researches of a new method of tensile stress determination.

PURPOSE. The article studies the dependence of the change in the maximum value of body displacement and the maximum value of the control amplitude of solid body protection object oscillations. METHODS. The efficiency of the two-stage method of parameter synthesis is analyzed. These parameters ensure specified requirements to the quality of vibration isolation taking into account a mathematical design model of the system of vibration protection from a given kinematic impact caused by harmonic and polyharmonic oscillations of the base. RESULTS AND THEIR DISCUSSION. It is shown that the problem of synthesis of optimal structures of the vibration isolation system can be reduced to the problem of parametric optimization. We treat the problem of parametric optimization of the vibration protection system as a problem of determining the optimal parameters of the object vibration isolation system under the selected (or given) structure and available complete information about the object and perturbations affecting it. CONCLUSIONS. It is determined that if vibration protection system is optimal the growth of the value α causes the increase in maximum displacement whereas the maximum value of the control function decreases. Therefore, choosing the weighting factor α we can achieve simultaneous fulfillment of the quality requirements for vibration protection and limit overall dimensions.