The paper is devoted to microeconomics of electric power industry with the focus on the technical aspects of electric energy production by thermal power plants. The PURPOSE of the paper is to study the features of calculating electrical energy supplier marginal costs and a corresponding supply curve for a day-ahead market on example of a specific power turbine. Such supply curves are important for theoretical market research in electric power industry, market design, regulation applied in the industry as well as for accurate operation of generation companies on a day-ahead market and balancing market. METHODS. The output performance of the steam boiler and the turbine Т-185/220-130 operating in a condensing mode has been used as input data. Mathematical modeling is applied to obtain short-term marginal costs (STMC) and a supply curve of a pricetaker. RESULTS AND CONCLUSIONS. It is shown that the function of short-term marginal costs of a supplier can depend on the plant operation mode which is determined by the market results. This inverse dependence arises if the composition of enabled aggregates changes within the time interval under consideration and this change causes additional costs. It is also shown that the function of short-term marginal costs of the energy supplier at the day-ahead market can have decreasing intervals due to the fact that energy equipment efficiency factor grows alongside with the load. In this case the supply curve of the pricetaker does not coincide with the function of marginal costs and can be ill-defined both in the range of output below the minimum safe output and within the range of technically achievable values of output capacity. It is also noted that it is important to take into account the limitations on short-term specific costs when calculating the supply function of suppliers-pricetakers. Moreover, the number of segments of the supply function of the pricetaker does not depend on the amount of CHP power units.

The PURPOSE of the paper is to consider the possibility of efficient purification of gases from small diameter solids (1-10 microns) by finely-divided particles precipitation on the H-beams of a rectangular separator designed by the authors as well as to study the effect of different initial velocities of the gas flow on particle deposition when they are in contact with separation columns. METHODS. ANSYS Fluent software package has been used to study the trapping of finely-divided particles whose diameter is less than 10 μm. Numerical simulation has been carried out through solving differential equations of motion and continuity. The turbulence model-SST has been used to close the system of equations. RESULTS AND THEIR DISCUSSION. The results of computer simulation and the analysis of the influence of gas flow velocity and solid particle diameter on separator efficiency are presented. The maximum efficiency of the separator is achieved when the gas flow rates are injected below 3 m/sec. CONCLUSIONS. The use of a rectangular separator increases the specific area of the contact surface of phases and simultaneously decreases the hydraulic resistance to the gas flow.

The PURPOSE of the study is calculation of the maximum permissible flows (MPF) of the controlled sections in the real time mode. The task of MPF determination is performed as a MPF estimation problem when using the method of weighted least squares of the sum of MPF estimation residuals. The desired solution is found by the selection of the weight coefficients of MPF pseudo-measurements (PM). The values of the weight coefficients of MPF PM are determined by the current operating conditions of the electric power system (EPS). METHODS. MPF estimation is based on the method of normal equations and the method of control equations used for solving the estimation problem of EPS state. The methods indicated above were slightly modified for MPF estimation. RESULTS AND THEIR DISCUSSION. The results obtained by the proposed method and the method of successive weighting have been subjected to comparative analysis. When the weight coefficients of the MPF PM are set correctly the MPF values calculated by the two methods coincide with the accuracy that does not exceed the measurement accuracy. CONCLUSIONS. The method of MPF estimation is presented. The measured MPF mode parameters and pseudo-measurements are used as input information. The proposed method enabled to calculate the resulting steady mode with the values of active flows within monitored lines, which are the maximum permissible in the current operating conditions of EPS when mode limitations are observed and all consumer obligations are fulfilled.

The PURPOSE of the paper is technical improvement of the charge-discharge electrotechnical complex of storage batteries and development of the structural diagram of an autonomous charge-discharge electrotechnical complex (ACDEC) with the monitoring of underwater device battery state. METHODS. To achieve the set goal the methods of mathematical modeling have been used as well as experimental researches on practical installations. RESULTS. A mathematical model of ACDEC is proposed in Matlab Simulink software. ACDEC charge-discharge modes are compared: voltage on the terminal at charge/discharge currents, dependences of voltage under the charge by currents, discharge current, capacitance, electrolyte density in the real time scale on models and a practical installation that have demonstrated good convergence of the results obtained. CONCLUSIONS. The components for the new structure of ACDEC are selected. The use of the diesel engine - a switched inductor-type generator extends the functionality of the introduced ACDEC ensuring its autonomy. The studies have shown that the error of voltage determination did not exceed 2.7%, the error of measured current determination was 2.74% and set current- 1,25% (which meets the specified requirements) when performing real time measuremens under the charge by the currents of 400; 900; 1800 и 3600 А.

The PURPOSE of the study is to determine the dew point in the flue gases of high-sulfur coals under their combustion in boiler units. METHODS. Pilot tests have been carried out on Novo-Ziminskaya CHPP boilers with the use of visual control devices and design characteristics. RESULTS AND THEIR DISCUSSION. The effect of the dew point alteration in the flue gases of high-sulfur coals and their mixtures on the operation of Novo-Ziminskaya CHPP boiler units BKZ-420-140 is studied. The main technical characteristics of the fuel are described. The technique of testing and processing of the obtained results is given. Based on the data obtained the dependence of SO₂ concentration on fuel sulfur content is constructed. The formula for the calculation of SO₂ content in flue gases depending on the sulfur content in fuel is determined. CONCLUSIONS. The dependence of the reduced sulfur content in fuel on its as-fired fuel sulfur content has been determined for the Azey coal. The content of sulfur oxide emissions in flue gases is strongly dependent on the as-fired fuel sulfur content. The dependences of SO₂ concentration in flue gases for the coal with the as-fired fuel sulfur content in the range from 0.5 to 1.9% on the dew point temperature reduced to the excess air factor in the flue gases have been determined.

The PURPOSE of the paper is to study the power system which contains wind turbines, photoelectric transducers, an electrolyzer for hydrogen production, fuel cells in order to determine the efficiency of electrical energy and hydrogen accumulation. METHODS. Based on the mathematical modeling an optimal structure of the power system has been selected and the operation modes of energy sources and storage devices have been studied in dynamics. Unlike the approaches known in the literature, the mathematical model used does not require preliminary setting of the operation modes of the system elements or the algorithms for energy switching between energy sources, load and accumulators. This allows us to investigate complex power systems which simultaneously produce and accumulate energy carriers of various types, in our case these are electrical energy and hydrogen. RESULTS AND THEIR DISCUSSION. Climatic and meteorological conditions that approximately correspond to the conditions of the southern part of Primorsky Krai and the middle part of Lake Baikal are chosen as input data. Technical and economic indicators correspond to the domestic and foreign equipment presented in the Russian market. Calculations are carried out both with and without restrictions on the introduction of specific technologies for their effectiveness evaluation. CONCLUSIONS. Mathematical modeling has shown the efficiency of the combined use of wind and solar energy in the areas under consideration as well as simultaneous accumulation of both electric energy and hydrogen. Accumulation of electric energy is most effective during short-term time intervals (output of electric power for several hours). If the duration of continuous no-wind and no-sun conditions increases up to several days the accumulation of hydrogen becomes more economical. The economic effect provided by the accumulation of hydrogen can reach 50% of the total effect under technical and economic indicators of equipment predicted for the next 10-15 years. The obtained results allow to substantiate the choice of equipment for consumer power supply in stand-alone power systems of small capacity.

The PURPOSE of the paper is to improve the efficiency of milling of large-size parts of panel-, beam-, spar-, frame-type made of high-strength materials on CNC machine-tools. METHODS. The study employs experimental methods to study the issues of milling modes intensification. RESULTS AND THEIR DISCUSSION. The study has been given to the cutting properties of modern tool materials produced domestically for milling high-strength stainless steels, titanium and aluminium alloys. CONCLUSIONS. Application of hard alloys of brands ВП322 and ВРК15 in the designs of single-purpose and special cutters intensifies milling modes by 1.3-2.5 times when machining large-size parts from titanium alloys and high-strength stainless steels. Hard alloy ВК8 intensifies the removal of metal by 3-5 times as compared with the tool made of high-speed steel when milling parts from aluminium alloys.

The PURPOSE of the paper is determination of the main parameters of the straightening process of low rigid cylindrical parts by transverse burnishing by flat plates that include the permissible initial deflection of the workpiece, general deflection of the workpiece before the transverse burnishing and the degree of relative reduction. METHODS. The work uses the mathematical apparatus based on the laws of the theory of elasticity of a solid. RESULTS AND THEIR DISCUSSION. The analytical calculations resulted in the determination of the main parameters of the process of straightening cylindrical parts by transverse burnishing by flat plates. The general deflection of the workpiece before transverse burnishing depends on the width of the plate overhang, mechanical properties of material and workpiece dimensions. The ultimate initial deflection depends on the material, diameter and rigidity of the workpiece. The limiting relative reduction depends on the friction coefficient between the workpiece and flat plates. CONCLUSIONS. A scheme of transverse burnishing by flat plates is proposed for straightening of small low rigid cylindrical parts of the shaft and axle-type. The straightening is performed due to the elastic bending of the workpiece in the direction opposite to the initial residual deformation and change in the stressed state by workpiece rotation between the flat plates. The developed mathematical model provides reliable values of bending deformations that arise after the straightening of parts by transverse burnishing by flat plates. The analytical dependence for the calculated determination of the limiting initial deflection, general deflection under bending and the value of relative reduction can be recommended for practical use in industry to achieve the precision accuracy of low rigid parts of the shaft type.

Today, the abrasive grinding of surfaces by flap wheels is widely used in aircraft construction under the manufacturing of large-sized parts. The main operating parameters of the process are flap wheel rotation frequency, longitudinal feed and wheel upset (deformation). At the same time, when grinding panels and skins featuring a non-constant curvature of the machined surface it is rather difficult to monitor and adjust the actual value of the flap wheel upset in operation. The solution is to use the drive effective power consumed for grinding as a mode parameter. In fact, the power consumed for machining is a complex parameter that in its turn depends on the rotation frequency, the value of feed and especially on the flap wheel upset value. However, it can be an effective mode parameter if frequency and feed rates are constant. The PURPOSE of the paper is testing the possibility of using effective power as a control parameter that determines the dynamics and performance of the grinding process. The METHODS used in the study involve analytical analysis and experimental verification. RESULTS. It is shown that the drive effective power can be successfully used as a control parameter of the process of grinding by flap wheels.

PURPOSE. The article presents the results of theoretical computation and practical studies of the Osipovs’ multi-purpose fire nozzle (OMFN) used for extinguishing of large-scale open fires of oil products, vehicles, woods, explosives, toxic substances and other materials. Consideration is given to the manual and hydraulic monitor fire nozzles of OMFN; the calculation method of their main performance characteristics is presented. Conducted experimental studies of the fire nozzles in field conditions allowed to give an unbiased evaluation of OMFN efficiency. METHODS. Micromanometric construction of flow rate diagrams is used to optimize the OMFN flow part. Performance indicators of existing and newly developed nozzles are compared by the method of field tests. RESULTS AND THEIR DISCUSSION. The study results have shown that OMFN have the greatest rate of the foam spray and feed the air-filled mechanical foam of average expansion ratio at the distance of 40-45 m. It is 10 m farther than the range of existing fire nozzles. Moreover, the foam produced by existing nozzles has low expansion resulting in low extinguishing capability. CONCLUSIONS. As compared with existing fire nozzles, the OMFN feature higher performances that proves the feasibility of their practical use.

The PURPOSE of this study is to identify the optimal design parameters of a vehicle equipped with a rotary screw propulsion unit under its rectilinear movement in wetlands. METHODS. A computer modeling has been conducted using Microsoft Visual Studio 2012 software to visualize the results. RESULTS AND THEIR DISCUSSION. The result of the mathematical modeling-based computer simulation is the determination of the maximum speed value V_max under different values of the pitch angle of the rotary screw propeller blade. CONCLUSIONS. The obtained values of speeds presented on a graph show that the maximum value of speed V_max is achieved at the pitch angle of 60º of the circular helix for all cases of rotary screw propeller vehicle movement on wetlands. It is determined that the 30º change in the pitch angle of the helical blade as compared with the basic pitch angle causes 2.68 time increase in V_max .

The PURPOSE of this work is additional recovery of nickel from aged and newly formed nickel dump slag by a thermodiffusion method. METHODS. The study employs the method of thermodiffusion comprising the transformation of nickel in slag in the halide compound with the following deposition on a steel substrate (iron shots) formed in slag under the recovery of iron contained in it. RESULTS AND THEIR DISCUSSION. An iron-nickel alloy containing 6.0-9.2% nickel weight has been obtained as a result of chemical and heat treatment of dump nickel slag with the following magnetic separation and smelting of the magnetic concentrate. CONCLUSIONS. The proposed method of additional recovery of nickel and cobalt from dump slags of nickel production allows to extract up to 80-85% of dump nickel and nearly 100% of dump cobalt into the end metal product - ferronickel using inexpensive reagents (undersized coke and ammonium chloride) and equipment.

SibVAMI JSC has developed a dry-type gas cleaning plant (DGCP) the technical concept of which is based on the modular design of a gas-cleaning installation. Being its components, the adsorber-reactor and bag filter provide a high purification level of electrolysis production exhaust gases and return the fluorine compounds adsorbed from these off-gases back to the process of electrolytic aluminum production. The fan provides gas movement through all sections of the DGCP gas path. Resistance minimization in these sections ensures a pressure drop sufficient for effective filtration on filter bags. It is very important to choose the design of “dirty” gas ducts with a minimum resistance. The PURPOSE of the paper is to optimize the design of flue gas ducts of dry-type gas-cleaning plants using a finite element modeling. METHODS. Different calculation methods have been used when developing the DGCP of SibVAMI JSC design. The main method was modeling of gas-dynamic processes by the finite element method. In particular, the modeling of dirty gas ducts has been carried out in the ANSYS CFX program. RESULTS. Modeling of gas ducts removing exhaust gases from the outlets from under the electrolysis pot rooms (“dirty” gas ducts) before the gas cleaning installation was performed for two possible schemes of gas ducts for which head losses were calculated. CONCLUSIONS. Optimal constructive decisions have been made when designing DGCP. The result of modeling is determination of a preferable design of “dirty” gas ducts enabling minimization of the head loss.

The PURPOSE of the paper is to study the thermochemical transformations occurring in limestone-nepheline mixture under sintering when technogenous additives are introduced. METHODS. Thermogravimetry, electron microscopy, mineralogical and x-ray diffractometric methods have been used in the study. RESULTS. It is proposed to introduce ferrotitanium slag in order to increase the content of alumina in limestone-nepheline mixture when sintering off-spec nepheline ore. It is shown that phase and chemical composition of ferrotitanium slag is not uniform since the slag is of technogenous genesis and contains many fine intergrowing mineral phases. The main minerals of the alumina containing slag are analcime (Na(Si₂Al)O₆×H₂O), montmorillonite (Al(OH)₂)_0.33Al₂(Si_3.67Al_0.33O₁₀)(OH)₂), hercynite (FeAl₂O₄) and iron replaced grossular (Ca₃Al₂(SiO₄)₂(OH)₄). It is noted that the behavior of minerals under limestone-nepheline mixture sintering differs significantly when ferrotitanium slag is introduced. It has been proved that slag minerals - analcime and montmorillonite - can be easily released in the process of caustic leaching. Grossular can be released in strong caustic condition only. Spinel hercynite (FeAl₂O₄) can not be broken down completely even in strong caustic conditions. Technological studies of limestone-nepheline mixture sintering with the addition of grounded ferrotitanium slag (100% -0.074 mm fraction) have shown the increase of alumina content in the sinter. CONCLUSION. Conducted thermochemical studies of ferrotitanium slag and its soda and limestone mixture calcination have shown that sintering temperature is about 1237°C. It is lower than the sintering temperature of limestone-nepheline mixture without slag additions. The results of technological tests of mixture sintering in the presence of ferrotitanium slag have confirmed the results of thermoanalitical studies. Addition of 5% of grounded ferrotitanium slag (100% -0.074 mm fraction) in limestone-nepheline mixture has increased the alumina content in sinter from 16 to 17.5-18.5%.

The PURPOSE of the paper is to discuss the features of logical mathematical modeling-based aggregate estimation of productive-economic systems. METHODS. The paper deals with the methods of expert estimation of the operation quality of productive-economic systems based on knowledge technologies. The study is based on modeling a system by means of the set of fuzzy productions and computing an aggregate evaluation as a logical inference based on the technology of expert systems. The paper discusses the issues of scoring of the functional elements, truth degrees for fuzzy productions as well as the problems of choosing the law of aggregation and additional transformations (calibration) of results. RESULTS. The result of this research is specified procedure of logical-axiological evaluation for productive-economic systems. CONCLUSIONS. The experts set the truth degrees of fuzzy productions by the combination of direct evaluation and ranking of system components in terms of value. The auditors assess the functional elements by the n-point scale taking into account the state of the elements. Aggregation is performed according to the “law of the least”. In general, the algorithm of logical-axiological evaluation must also include the calibration of result.

The PURPOSE of the article is to improve the efficiency of simulation modeling in various subject domains through the use of piecewise linear functions that allow high accuracy in the determination of arbitrary random variables. METHODS. It is proposed to use piecewise linear functions to specify the density of random variables under the transformation of a standard random variable to build simulation models. RESULTS. Based on the type of the random variable density specified by a piecewise linear function three algorithms of action sequence have been proposed for generating the mixture of the components that must have a defined discrete probability distribution. CONCLUSION. Due to their versatility the piecewise linear functions when applied provide sufficiently high generation accuracy of arbitrary random variables. A high simulation efficiency of piecewise-linear functions can improve the accuracy and adequacy of simulation models in different subject domains.

CONCLUSIONS. It has been determined that the applied control methods of cellular concrete production process do not meet modern requirements of consistent high quality product manufacturing. The requirements for a new control system for non-autoclaved aerated concrete products manufacturing are formulated on the basis of the performed analysis. The designed system will eliminate the existing shortcomings. ABSTRACT. The PURPOSE of the paper is to study the automation level of production lines used for cellular concrete products manufacturing. METHODS. The research was carried out based on the study of scientific and technical literature on the problem under consideration. RESULTS AND THEIR DISCUSSION. Today automated control systems of cellular concrete production process have two-levels. The upper level includes the workstations of operators while the lower level consists of microcontrollers and actuators. The levels interact through local networks. Technical staff generate control solutions which causes a number of critical flaws, such as, failures to take account of all influencing factors. A great responsibility for correct decisions rests with decision-makers. The authors of this article suggest a decision support system to be included in the control loop which will improve the quality of the decisions made under uncertainty.

PURPOSE. The modern practice of engineering calculations of part material strength uses averaged mechanical characteristics obtained through the standard tests of samples. In real conditions, it is strongly advised to avoid this averaging in order to minimize the errors when constructing the mathematical models of deformable solids using a finite element method. METHODS. In this paper, we propose a new approach based on the scanning of deformable solids using computed tomography. However, a series problem hinders the implementation of this approach: accurate identification of the scanned deformable solid relative to a real object by geometry and mechanical properties of material require an extremely large amount of data (information). RESULTS AND THEIR DISCUSSION. This problem is solved through the use of mathematical modeling and an algorithm for processing bitmap images of deformable solid sections enabling to construct the variations of mechanical characteristics of its material and geometry. The key algorithm of the presented mathematical modeling is the use of pixel characteristics of computed tomography images. Also, the necessary component of the algorithm is the use of data obtained via full-scale testing of samples. Assuming the wide use of computed tomography for medical purposes the fragments of human femur and jaw have been chosen as the objects of the study. This choice is determined by the specificity of their geometry and explicit heterogeneity of the bone material. CONCLUSION. A finite element model of a deformable solid with a real distribution of mechanical characteristics of material and individual geometry has been developed. The stress-strain state has been analyzed on the basis of the model.

The object of research is the boiler unit of the Irkutsk combined heat and power plant (CHP). The paper studies the effect of temperature in the boiler unit rotary chamber on the qualitative parameters of the process of superheated steam production: steam capacity, steam pressure at the outlet and the temperature of saturated steam in the drum. The PURPOSE of this work is development of a mathematical model of a combustion unit taking into account the dynamics of the object that will allow more accurate prediction and control of the process of steam production as compared with classical automatic control systems. METHODS. Since the complex structure of the object of research does not allow to use the classical methods for estimating parameter interrelation we can only observe the reaction of output values on the variation of input values. It is proposed to use the methods of J. Box and G. Jenkins (integrated autoregressive moving average model) to identify the process of steam production with a conditionally unknown internal organization. The software package “Statistica 6” is used to perform the statistical analysis of time series. RESULTS AND THEIR DISCUSSION. The boiler unit is described as a dynamic stochastic object with uncontrollable disturbances. Using experimental and statistical methods, a mathematical model has been obtained that allows to determine the degree of temperature influence in the rotary chamber on qualitative parameters in steam production. CONCLUSIONS. Dynamic stochastic models have been developed by selected channels. The obtained models have been subjected to diagnostic testing. The developed models can be used for prediction and control of the process of steam production.

Existing methods of maintenance periodicity adjustment don`t take full account of the negative impact of factors on which the operation efficiency of cargo transport and drivers’ safety on the route depends. The problem of ensuring the efficient use of cargo transport and drivers’ safety in complex operating conditions is highly relevant. The PURPOSE of the work is formation of the severity levels of cargo transport operating conditions depending on the factors that limit their reliability, as well as improvement of the methodology of maintenance periodicity adjustment using remote diagnostic tools. METHODS. The study uses an a priori ranking method, a correlation-regression analysis as well as the methods for determining the accumulation rates of the vehicle load effect. RESULTS. Four levels of operation condition severity have been identified including acceptable, averaged, increased and critical. The mathematical models confirming their existence have been obtained. The values of the load effect for the different severity levels of cargo transport operation have been determined. CONCLUSION. The results obtained provide an opportunity to form the maintenance mode adjustment factors for different brands and models of cargo transport taking into account the operating conditions.

The PURPOSE of the paper is to improve the efficiency of AC electric locomotive in the regenerative braking mode under control pulse skip supporting the inversion process and retaining the electric locomotive braking force. METHODS. The study uses the following methods: mathematical modeling, numerical methods for solving integral and differential equations, the theory of transforming devices. The experiments were carried out using a mathematical model “traction substation - catenary network - electric locomotive" in MatLab Simulink environment. RESULTS. Electromagnetic processes has been analyzed in electric locomotive power circuits under control pulse skips to the thyristors of one of the shoulders of the reversible converter. The curves of generator currents and inverter voltages have been obtained in the course of mathematical modeling of the electromagnetic processes of the electric locomotive inverter in the mode of regenerative braking under control pulse skips. CONCLUSIONS. Having analyzed the curves of generator currents and inverter voltage we have proposed a technical solution that enables to improve the efficiency of AC electric locomotive in the regenerative braking mode that is implemented through changing the software of the microprocessor control system of an electric locomotive. The developed solution allows to support the inversion process and retain locomotive braking force.