The purpose of the article is to consider the estimation methods of the efficiency of diesel power stations switch to alternative kinds of fuel. To provide isolated remote areas of the Far North of Russia with electric energy, diesel power stations are used, which require expensive imported diesel fuel. The cost of the produced electric energy ranges from 10 to 20 rubl/kWh. Development of mineral resources such as natural gas, oil in these areas allows to transfer local diesel power stations to other kinds of fuel. This switch requires a significant investment in the modernization of existing diesel power stations substantiated by a feasibility study of the switch to other fuels. The study uses official data, methods of comparative analysis and author’s calculation results. The calculations are made on the basis of the production and financial model. The world practice of investment project economic efficiency assessment is briefly characterized. A method to estimate the efficiency of existing diesel power stations switch to alternative types of fuel (natural gas) is presented. The representatives of the energy-saving policy propose a gradual transition of existing diesel power plants to alternative types of fuel that are economically and technically more advantageous in certain conditions of remote areas of the Far North. On example of existing diesel power plant switch to natural gas an opportunity has been received to evaluate the high efficiency of the project.

The purpose of this work is to describe an improved procedure for parameter identification (adjustment, verification) of mathematical models of complex thermal power equipment. This procedure allows more efficient detection of gross errors in measurements of control parameters used for the identification of the mathematical model of the operated equipment. It also evaluates the accuracy and allows to correct the construction errors of the model itself increasing identification accuracy. Besides, the paper describes an original approach to consideration of the effect of a generating unit load on the internal relative efficiencies of turbine compartments. It can be applied to other adjustable coefficients of the mathematical model with the nonlinear dependence on equipment operation modes. The improved identification methods of mathematical models have been tested on the detailed mathematical model of the contemporary 225 MW generating unit designed by the author. The article presents the results of solving the identification problem of the generating unit mathematical model and an example of the optimization calculation of the real operation mode aimed at decreasing specific fuel consumption for electricity generation.

The purpose of the work is to analyze the electromagnetic field generated by the AC traction network of 25 kV at railway stations. The study applies the calculation methods of electromagnetic field intensity and Poynting vector on the basis of determination of the modes of traction power supply system in phase coordinates implemented in the program complex «Fazonord». The calculations of intensities of railway station electromagnetic field show the complexity of traction power supply systems due to the large number of tracks and catenary lines, lasting presence of metal railway cars and tanks on station tracks. Moreover, the distribution nature of the electromagnetic field is influenced by metal pipelines, fences and reinforced concrete passenger platforms. When the power transited through the contact network of the station is 10 + j10 MV·A, which is close to the limiting load capacity of one traction transformer with the capacity of 40000 kV·A, the intensity of the magnetic field at the level of 1.8 m (due to the distribution of the current load on the contact networks of several tracks) is significantly lower than the magnetic field intensity at the haul. The amplitude values of the magnetic field intensity in calculated examples do not exceed 30 A/m. The presence of rolling stock significantly reduces the density of electromagnetic energy flow on passenger platforms, as well as the level of adverse effects of the electromagnetic field on the human body. Cars and tanks positioned on the tracks of the station cause a 2 times decrease in the intensity of electric and magnetic fields. However, the availability of an underground pipeline near the station tracks causes an increase in the magnetic field intensity in the area above the pipeline (due to the currents existing on the pipeline). The article also provides the calculations of field variation in time determined by the train traffic. This allows to obtain the most complete picture of electromagnetic safety conditions at railway stations.

The purpose of this article is the study of various implementation methods of the field attenuation system of traction motors of DC and AC electric locomotives as well as identification of their advantages and disadvantages. Taking into account the discussed methods a field attenuation system of traction motors of DC and AC electric locomotives with an energy-saving control method designed on the basis of IGBT-transistors has been developed and proposed. The study uses the method of comparative analysis of devices, operation principles, advantages and disadvantages of various implementation methods of the field attenuation systems of traction motors of DC and AC electric locomotives. Consideration of the existing field attenuation systems of traction motors of DC and AC electric locomotives allowed to reveal all their shortcomings. The analysis of the modern scientific works of scientists and specialists devoted to the improvement of the field attenuation system of traction electric motors resulted in the conclusion that all the works are aimed at eliminating the inductive shunt from the power circuit providing reliable protection in non-stationary operation modes of the electric locomotive. Having considered the shortcomings of various implementation methods of the field attenuation systems of traction motors, an improved system has been proposed that allows to replace the inductive shunt with an IGBT-transistor with an energy-saving control algorithm. The system is able to provide reliable protection in non-stationary operation modes of the electric locomotive.

Experimental studies of heated materials with the surface temperature from 313 to 363 К transported by conveyors in production conditions were carried out in order to obtain the data required for the design of heating and ventilation systems of conveyor galleries. Experimental researches were conducted analytically on a laboratory test bench, which allowed to simulate actual conditions corresponding to production ones as accurately as possible. The factors influencing the heat exchange of heated materials with the temperature from 313 to 363К under conveyor transportation have been identified. Calculated dependences have been obtained for determining heat release from the surface of these materials. The data provided in the present work can be considered more reliable than the data of the authors of previous studies, since the studies carried out by the latter were conducted with the use of less advanced equipment which lacks the capacity of accurate simulation of actual production conditions. The empirical dependences that enable the determination of local and average coefficients of general and convective heat transfer at conveyor transportation of materials with the temperature from 313 to 363К have been received, and the heat flux coming from heated materials’ surface calculation has been calculated. The obtained data are necessary when designing heating and ventilation systems for production rooms where conveyor transportation of heated materials with the temperature of surface from 313 to 363К is carried out.

The purpose of the work is development and study of three-phase bridge rectifiers and inverters. It is achieved through the use of simulation methods in SimPowerSystems/Simulink of MATLAB. The article proposes the models of an uncontrolled and controlled three-phase bridge rectifier, an autonomous bridge inverter, an autonomous inverter with stabilized voltage, a network driven three-phase bridge inverter in SimPowerSystems/Simulink of MATLAB. The research conducted on the developed models has shown the correctness of the use of mathematical apparatus and semiconductor device control principles. The developed models can find application in the studies of power supply systems containing renewable energy sources (such as solar cells), which can be used together with electrical energy storage devices requiring inverters and rectifiers to be connected to the electrical network.

The purpose of the article is to form differential equations of a new mathematical model and a system of equations for constructing the steady-state and transient operating modes of single-phase power transformers with identical secondary windings. These transformers are widely used as furnace transformers in the ferroalloy industry and metallurgy. To protect the specified transformers from short circuits, current protection is introduced, which should be produced with regard to their operating conditions in stationary and transient activation modes. Single-phase furnace transformers with a split secondary winding are distinguished among power transformers. The splitting of the secondary winding is represented by identical single-turn insulated windings performed by a bus with a large cross section. To simulate currents in the transformer windings in an arbitrary operation mode it is reasonable to use a mathematical model the differential equations of which are composed according to the second Kirchhoff law. In this case, the number of equations in this mathematical model will be equal to the number of windings and their elements in this transformer. This will make it impossible to use iterative methods (for example, the well-known Gauss method) for calculating currents in transformer windings as the number of operations in these methods depends on the calculation error. However, the solution of the system of differential equations for a multi-winding transformer is quite a challenge. In this regard, a method of replacing all identical secondary windings with one equivalent is proposed. Taking this into account, the authors have formed differential equations of a new mathematical model, as well as a system of equations for modeling steady-state and transient operation modes. The adequacy of this model has been tested in a stationary mode by comparing simulation and experimental results.

The purpose of the article is to develop fuel and energy balances of eastern regions of Russia (Siberia, the Far East); using promising fuel and energy balances and statistical methods to predict energy intensity of the gross regional product (GRP) of the eastern regions and the costs of technological innovation required for the growth of energy efficiency. The study is based on the methods of economic and mathematical modeling, system analysis, correlation and regression analysis, balance methods. The methodical approach developed by the authors develops already existing theoretical knowledge in this subject area. Reporting and forecasting fuel and energy balances of Russian eastern regions have been compiled. A long-term forecast (for the period up to 2040) of fuel and energy balances and GRP energy intensity dynamics in the eastern regions of Russia have been fulfilled using the system of economic and mathematical models. To achieve the calculated levels of reducing the GRP energy intensity, a forecast of the increase in the technological innovation costs in the economy of this region has been made. The conducted study implies that GRP energy intensity in the eastern regions of Russia according to a moderate development scenario can be reduced by 56-75% (as compared with 2016). It will require both structural changes in the fuel and energy balance and an increase in the cost of technological innovations by the end of the period under investigation up to 4.4-4.7 billion dollars (by 31-38%). In the case of more optimistic development forecasts for the fuel and energy complex of the studied region (under the moderate scenario of socio-economic development), the GRP energy intensity may decrease by 1.8-2.2 times by 2050 as compared with 2016, which will require the growth of annual costs of technological innovations up to 4.8-5.1 billion dollars (by 41-50%).

The purpose of the paper is to improve the efficiency of mechanical processing of parts from hard-to-machine materials by using special designs of face mills with variable cutting patterns. The study uses experimental and theoretical research methods of improving the performance of required designs of face mills with disposable hard alloy inserts for the processing of hard-to-machine materials at their design stage. The method of designing special constructions of face mills with disposable hard alloy inserts for milling of hard-to-machine materials for both rough and finishing machining has been developed. The use of computational methods allows to eliminate the influence of subjective factors on design quality and reduces design complexity. The use of special face mills with disposable hard alloy inserts operating with reverse shavings increases the efficiency of both rough and finishing machining of parts from hard-to-machine materials and from 2 to 10 times intensifies metal removal as it was proved by the results of laboratory and production testing. In some cases they are the only possible machining option in production conditions.

The purpose of the article is to create an automated system of the technological process of wood drying that allows to research the physical processes, which take place in the drying chamber. The study employs a combined method of timber drying, which integrates an oscillating mode and natural circulation including the short-term cyclic opening of the outlet valve of the drying chamber with the periodic start of the forced circulation. The algorithm of the combined mode of timber drying is developed. A functional diagram of the automated system of scientific studies of the technological process of wood drying is proposed. A scheme of the ordered automation of the scientific studies of the technological process of wood drying is implemented. It allows both to control the process of wood drying and study the physical processes occurring in the drying chamber. An automated control stage of the specialized developments of the technological process of wood drying is based on the use of modern information-control devices, such as a programmed logical controller, microprocessor regulators and an industrial frequency converter.

The purpose of the paper is to determine the values of elastic movements of mandrels when assessing the stress-strain state of modular constructions of a spindle-instrumental mandrel designed on the basis of conical detachable profile joints under static loading, and to estimate the accuracy and durability of a conical detachable profile joint designed for torque transmitting and featuring an equiaxial contour with a number of faces equal to three spindle-instrumental mandrel assemblies. The methods of numerical solution of elasticity theory problems including the finite-element method (FEM) as well as the methods of mathematical statistics and computer technology are used to study the stress-strain state of the modular system of an auxiliary tool based on profile joints. The paper provides the results of a complex research, the stress-strain state of modular structures of the multi-purpose machine-tool spindle assembly, namely: a modular system of an auxiliary tool based on profile joints with the equiaxial contour. The article analyzes the influence of design parameters of a conical profile joint, retaining pressure (with the fixation method by the magnitude of the assembly force), values of limiting external loads and friction forces on the accuracy and strength of spindle-instrumental mandrel joint with a profile mounting surface of the shank for actual dimensions of the modular design of the assembly. The values of elastic displacements of instrumental mandrel sections along the mounting length of the profile joint are determined with the use of the mathematical apparatus of the finite-element method based on spline approximation and a variation-energy principle of the displacement method of the elasticity theory. The calculation is performed of the values of elastic displacements of a mandrel and stresses in radial, normal and circumferential directions by the volume of the instrumental mandrel and spindle. Software in FEMAP 11.1 environment with NX NASTRAN has been applied for calculations. It has been determined that the values of elastic displacements of instrumental mandrel sections change nonlinearly and their value at the end face does not exceed 1.8 µm under the limiting external loads of the joint. Accordingly, the maximum values of the normal contact stresses in the extreme sections of the spindle do not exceed 7.71 MPa.

The purpose of this paper is to develop a methodology for determining the input parameters of high-frequency equipment in order to perform diagnostics in the automatic mode as well as to improve the quality of products made of polymeric materials under conditions of modern production. Having considered a high-frequency control method for the products from polymer composite materials the paper substantiates the choice of the high frequency diagnostic method as the most suitable for non-destructive testing. Description is also given to the existing problems of technological operations of diagnosing and improving of polymer operational properties. The set goal is achieved through the analysis of research works and conducted experimental studies in this area. The main control parameters and the process of high-frequency radiation exposure of the products of various shapes and sizes are specified. The paper presents graphic results. A software package has been created that calculates the parameters of product diagnosing in the automation mode. The results of experimental studies are provided and estimated in order to prove the hypotheses put forward and the adopted mathematical solutions for input parameter selection. A methodology has been developed for determining and setting the main parameters of high-frequency equipment in order to implement the diagnosing and improve operational properties in the automation mode.

The purpose of the paper is to develop mathematical models and algorithms based on the finite element method to analyze the sensitivity of vibrations of machine parts and structural elements to changes in design parameters. The paper presents an algorithm for sensitivity analysis based on the finite element method, as well as the calculation results of sensitivity of compressor blade free oscillations to the changes in its profile thickness. The finite element method in displacements is used. The classical Gauss method is used to solve the systems of linear algebraic equations. As a result of conducted researches the developed method of frequency sensitivity coefficients is offered for the analysis of oscillations. Based on the developed mathematical models, algorithms and methods the analysis of the rotor blade eigen oscillation sensitivity to the changes in profile thickness is analyzed. The calculation results have shown that the error of the frequency prediction by the sensitivity coefficients is small as compared to the calculation of the modified models. Consequently, the sensitivity coefficients can be used to assess possible designs of the blade. The presented calculation results demonstrate a rather small error, which allows to apply the developed analysis method of eigen frequency oscillation using sensitivity coefficients for the optimal design of the gas turbine rotor blades. The use of sensitivity coefficients provides the possibility to estimate the effect of the change in the local profile thickness on the blade oscillation spectrum. This significantly increases the efficiency of work on structure optimization when designing it.

The purpose of the article is to consider the issues of strength calculation of products (on example of a striker) receiving short-term loads. The method for calculating the strength of the main structural element of the mechanism of the real calculation problem of a striker- a device that is used together with a construction perforator is presented. The calculations allow to determine the best dimensions of the striker head shape. In this case, the perforator sets a short-term force acting on the tool (striker), which is spent on moving and heating of the tool elements and partially returns back to the perforator mechanism. The impact energy can reach up to 20J, the frequency of the construction perforator shock load is in the range of 17-35 Hz. The experiment has showed that in addition to static strength calculations, it is also necessary to carry out a frequency analysis of the critical values of eigen frequencies of the structure. The results obtained are analyzed for normal and maximum allowable stresses. A method for determining the static load of the structure and its dynamic coefficient under the influence of periodic shock load is developed. The performed calculations of static loading and harmonic analysis allow to determine the structural strength of the designed product, select workpiece material and determine the dynamic coefficient. The proposed calculation method can be used both for solving the problem described in the article and for the whole class of problems with the shock load, which take into account the time of force application or duration of the force pulse.

Improving the quality of refractories and decreasing the specific consumption of these products per a production unit through using of modern resource-saving processes is a highly relevant task in manufacturing refractory materials for metallurgical purposes. Strength and porosity are important indicators affecting operational properties of refractory materials. The object of research is refractory products made of clay from Beloe Glinishche field (Karaganda region) in a clay bond. The use of raw materials of the Kazakhstan origin reduces the product costs, decreases the import of goods, and on the condition of receiving refractory materials with higher mechanical and operational characteristics, gives the prospect of product export. The porosity of refractory products made of clays from various fields is determined. The effect of chamotte mixture moisture content on the compressive strength of refractory products is identified. It is found out that the most expedient is the following technological mode of refractory product manufacturing: pressing of samples from furnace charge for 12 seconds, (initial) pressure is 22 MPas which in 7-8 seconds has been increased up to 27 MPas. Then sintering has been carried out at the temperature of 1250-1270 °C for 12 hours. The use of the clay from Beloe Glinishche field in the composition of a clay binder allows to achieve uniform porosity and higher strength of the product.

Improving corrosion resistance of heating pipe stills with the use of a special corrosion inhibitor SNPH - 6030 “B” is an economical method and is very important for the oil industry, since complete replacement of damaged by corrosion pipe still coils is a very costly process. The presence of heavy metals, metal compounds and other impurities in crude oil adversely affects the corrosion resistance of oil refinery equipment and installations. Modern methods used in the study including chemical analysis and atomic absorption spectroscopy (using VARIAN-SPECTRA AA 220 FS device) were carried out with the application of an analytical scanning (raster) electron microscope VEGA3 TESCAN. Micro X-ray spectral analysis of the composition of phases present in coiled-pipe materials was carried out by the method of energy dispersive x-ray spectroscopy on Oxford INCA Energy EDS spectrometer. The method of weight loss was used to analyze the corrosion ability of the coil. The conducted studies have shown the formation of pitting corrosion that can be attributed to the electrochemical type. The proposed inhibitor is effective in terms of increasing the corrosion resistance of pipe still coil material due to corrosion rate reduction. The best results were achieved using the selected inhibitor under the following conditions: duration ̶ 48 h, inhibitor concentration - 0,02 wt.%, temperature - 100 °C; effectiveness of corrosion rate reduction under these conditions reached 97,94%.

The purpose of the paper is to calculate heating of a steel rod (a crystallizer), determine its heating time up to the predetermined temperature and estimate the temperature to which the metal heats up if it is partially submerged in the aluminum melt. The heating of the steel rod immersed in the molten aluminum is calculated in the temperature range from 670 to 810°С. Based on the conducted calculations of the crystallizer heating, a new method of technical aluminum refining is proposed and its efficiency is substantiated. The presented method involves iron and silicon impurities extraction from the aluminum melt through its rapid cooling by the introduction of a massive steel body (a crystallizer) into the surface layer of metal. It is found out that the difference between the temperature of the rod end immersed in the melt (hot end) and the temperature of molten aluminum (rod holding time in the melt is 30s; immersion depth - 5 cm) is in the range of 226-260°C. Significant temperature head between the crystallizer and aluminum melt provides the possibility to use the proposed method for deep refining of technical aluminum.

Abstraсt: The purpose of the paper is to study the process of obtaining Mg-REM master alloys and determine the list of factors of the metallothermic magnesium process in order to identify optimal technological regimes. The study uses different modern methods of analysis. The X-ray fluorescence analysis was carried out using the XRF-1800 sequential X-ray fluorescence spectrometer (Shimadzu, Japan). Phase identification was performed with the use of the X-ray powder diffractometer XRD-6000 (Shimadzu, Japan). The complex thermal analysis was carried out using the STA 429 CD (NETZSCH, Germany) installation in alundum crucibles with lids in the argon stream using a Tg+DTA crucible holder. Master alloys of Mg-REM with different percentages of alloying elements have been obtained as a result of the metallothermic magnesium reduction of neodymium and gadolinium from fluoride-chloride melts. The proposed method of REM reduction from fluoride-chloride melts allows to extract neodymium and gadolinium in a percentage up to 97.4%. The obtained master alloys are homogeneous and fluid, well poured into molds.