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Naukovi visti NTUU “КPІ”. – 2015. – N 6



Short-term forecasting of macroeconomic processes with regression and probabilistic models / Bidyuk P.I., Trofymchuk O.M., Karayuz I.V. - K.: Naukovi visti NTUU “КPІ”. – 2015. – N 6

Background. Today there is a problem of constructing high quality mathematical models for short-term forecasting of macroeconomic processes. The most often approach used for solving the problem is based on regression models though there are also developed competitive probabilistic models that exhibit high forecasting quality in conditions of uncertainties of various kind and nature.

Objective. To perform analysis of current economic situation in Ukraine using statistical data; to construct regression models suitable for short-term forecasting of macroeconomic processes selected; to provide a generalized methodology for constructing probabilistic models in the form of Bayesian networks and to construct appropriate network models for macroeconomic processes; to perform necessary computational experiments aiming to model parameter estimation and compare quality of generated forecasts.

Methods. To solve the problems stated two basic approaches to construct mathematical models are hired: regression analysis and Bayesian networks constructing using statistical data and expert estimates. A generalized multistep methodology is developed for Bayesian belief networks constructing that uses statistical data and other possible prior information.

Results. The models resulted from regression analysis of actual data provide a possibility for generating short-term forecasts of GDP though not always of high quality. Another model was constructed in the form of a Bayesian network. The model turned out to be better than the multiple regression, it provides quite good estimates for probabilities of GDP growth direction.

Conclusions. It was shown that application of regression models for describing macroeconomic processes of economy in transition not always finalizes with positive results. This can be explained by numerous out-of-market events (factors) that influence development of the economy. The short-term forecasting results obtained in this case are not always of high quality though quite acceptable. On the other hand probabilistic models such as Bayesian networks provide a possibility for obtaining well substantiated probabilistic estimates for the direction of GDP growth in Ukraine. A substantial advantage of the simple heuristic method used for constructing BN is in its transparency and small number of computing operations.

Keywords: macroeconomic processes; forecasting; regression analysis; Bayesian networks.

Optimal Control Problem by Linear Dynamic System of the Second Order /Kopets M.M. - K.: Naukovi visti NTUU “КPІ”. – 2015. – N 6

Background. For controlled object which behavior is described by the system of two linear differential equations and with criteria of quality in the form of quadratic functional the optimal control problem is considered. In contrast to the general used methods for investigation of this problem (Pontryagin’s maximum principle, Bellman’s method of dynamic programming) the Lagrange’s multipliers method is proposed by author. Such approach provided the possibility to more effectively obtain the solution of the investigated optimization problem in comparison with the above-mentioned methods.

Objective. The purpose of the research is to obtain the formulas for calculation of optimal control and minimal value of the cost functional.

Methods. In the paper the methods of calculus of variations were used.

Results. In the paper the necessary optimality conditions were obtained and the uniqueness of optimal control was proved. On the basis of these conditions the system of differential Riccati equations is deduced.

Conclusions. The solution of this system permits to write the closed formula for optimal control and formula for calculation of minimal value of the performance functional. The results obtained in the paper may be used for investigation of the process of landing of airplane.

Keywords: quadratic functional; method of Lagrange multipliers; necessary conditions of optimality; optimal control; system of differential Riccati equations.

Regulation of Removal Process of Non-Metallic Inclusions at Secondary Treatment of Melt /Bogushevsky V.S., Gorbachova M.V. - K.: Naukovi visti NTUU “КPІ”. – 2015. – N 6

Background. When secondary refining with inert gases, blowing intensity of metal is generally maintained at a constant level and limited by the level of metal in the ladle. Recent studies show that the blowing intensity effect to remove impurities of different size, so there is the problem of regulating this process.

Objective. The aim of the investigation is to research the process of removing non-metallic inclusions from the metal in the ladle by blowing an inert gas in order to increase the efficiency of removing impurities and preventing the emission of metal from the ladle when blowing.

Methods. The regulation of removing non-metallic inclusions from steel by changing the blowing intensity in ladle is described. The structural scheme of regulation circuit to control the process of purging the metal in the ladle is created. An example of regulation of removing non-metallic inclusions from steel in the 160-ton ladle has been given.

Results. Changing the blowing intensity, giving it a fluctuating nature, in which the maximum intensity is the minimum size of nonmetallic inclusions to be removed and the minimum - maximum possible size of inclusions and frequency - a free ladle capacity, increased efficiency removal of inclusions has been established.

Conclusions. It is shown that the determination of probability size of inclusions and free volume of the ladle to regulate the blowing intensity of metal, improve mixing of metal in the ladle warning metal emissions and ensure complete removal of non-metallic inclusions of various sizes.

Keywords: blowing intensity; ladle; non-metallic inclusions.

Precision Machining of Wear-Resisting Friction Parts’ Plane Surfaces from New Composite Materials Based on High Alloy Steels for Technological Complexes /Gavrish А.P., Roik Т.A., Zigulia S.M., Vitsuk Iu.Iu. - K.: Naukovi visti NTUU “КPІ”. – 2015. – N 6

Background. Researches of fine processes of precision machining of wear-resisting friction parts’ plane surfaces from new composite materials based on die and instrumental steel wastes for technological complexes of printing machine building enterprises and also for machine tool systems of light and food industries of national economy of Ukraine were presented in the article.

Objective. The purpose of this paper is to determine the quality parameters of precision machining with such new composite materials as 85Х6НФТ, 11Р3АМ3Ф, Р6М5К5, Р6М5Ф3, 4ХМФТС, 4Х2В5МФ and also to determine the effect of technological processing parameters on quality indexes of treated surfaces.

Methods. Fine processes of precision machining of friction parts’ plane surfaces were carried out with C-15 machine tool. Disc material for fine machining is cast iron. As abrasive finishing micropowder s were used grains of white chrome electrocorund with the percentage composition of chromium oxide from 1.0 to 2 % (32A), titanium electrocorund with the percentage composition of titanium oxide from 1.5–2 % (37A), borazon (BN) and artificial diamond (AC). Granulosity of abrasive powders for fine machining is 1–14 μm. Composition of lubricating cooling liquid was mixture of kerosene (70 %) and industrial oil U16 (30 %).

Results. It was demonstrated the technological factors of fine precision machining development such as cutting parameters, material and granulosity of abrasive powders for fine machining and also composition of lubricating cooling liquid essentially influence the quality of surface’s parameters of researched parts. The best results were obtained when using cast iron discs for finishing precision machining development, grains of artificial diamond (AC), borazon (BN) and white chrome electrocorund with the percentage composition of chrome oxide from 1.0 to 2 % (32A) with granularity 1–14 μm and at the same time with use of kerosene             (70 %) + industrial oil U16 (30 %) mixture.

Conclusions. For the first time it was shown the main regularities of fine precision machining parts’ plane surfaces from new composite materials based on stamp and die steel wastes meet fundamental regulations of super fine abrasive grinding in general theory. The recommendations for choice of cutting parameters for different technological purpose that are manufactured from composite alloys based on stamp and instrumental steels wastes are developed.

Keywords: new composite materials; friction parts; precision machining; fine-grain abrasive powders; technological processes of treatment.

The Structure and Protective Properties of Complex Chromium, Titanium, Aluminum Based Diffusion Coatings on U8A Steel /Loskutova T.V. - K.: Naukovi visti NTUU “КPІ”. – 2015. – N 6

Background. Modern materials work under stringent conditions of simultaneous action of high production speeds, high temperatures, aggressive environments, and therefore the materials they are made of must have an integrated protective properties: to combine wear resistance, high crack resistance, chemical stability at elevated temperatures, high corrosion resistance. Despite the large number of known types of coatings and their methods of obtaining scientific aspects of creation of coatings with a wide range of protective properties is not sufficiently developed.

Objective. Study of phase and chemical compositions, structure and protective properties of coatings on U8A steel, obtained by combining of diffusion chromium plating with the subsequent titanium aluminizing.

Methods. The coating was applied on the surface of the U8A steel. On the first stage, the gas plating at a temperature of 1050 °C for 4 hours was carried out. On the second stage titanium aluminizing of powder coat at a temperature of 1050 °C for 4 hours was carried out. X-ray diffraction, electron-probe, metallographic, durometric studies were conducted using known methods of physical materials science. Corrosion tests by gasometrical method were carried out.

Results. It is shown that as a result of saturation on the steel surface a multilayer coating is formed consisting of carbides of chromium, titanium, intermetallic compounds of titanium, aluminum, chromium. It has been established that the microhardness of multilayer coatings based on chromium carbides, titanium carbides, intermetallic metals is 5.8–34.0 GPA. It is shown that the application of complex coatings based on chromium, titanium, aluminum increases the resistance of U8A steel in many aggressive environments.

Conclusions. Complex chromium, titanium, aluminum saturation of U8A steel allows obtaining coatings with a total width of 27.5–30.5 µm, which ensures high corrosion resistance in various industrially important aqueous corrosive solutions.

Keywords: steel У8А; diffusion coating; plating; titanium aluminizing; corrosion resistance; microhardness.

Investigations of Processes of Compacting of Tribotechnical Powder Materials Based on Dispersed-Strengthened Copper / StepanchukА.M., Bogatov A.S., Biryukovych L.O. - K.: Naukovi visti NTUU “КPІ”. – 2015. – N 6

Background. Creation of theoretical and technological foundations of antifriction powder materials using dispersed-strengthened copper powders is urgent task, requiring a dependency determination of properties of the final product on the conditions of its receipt.

Objective. The purpose of this paper is to study the processes of obtaining products from powder materials based on dispersed-strengthened copper by hot stamping of current collector by electric vehicles. Determine the effect of parameters of stamping to form density, structure and some properties of the piece – hardness, flexural strength and specific electrical resistivity.

Methods. A processes research technique of products compacting from powder materials by hot stamping was proposed. Density, structure and properties research was conducted using modern techniques and equipment to study the mechanical properties, optical and electron microscopy, computer technology.

Results. Processes of compacting of antifriction materials of based dispersed-reinforced copper were investigated. Dependence of properties on the conditions of their production  stamping power, temperature and heating time of initial blanks before stamping was established. It was show that under certain conditions stamping density material greatly increases with the stamping power gain to 200 N×m/cm3 and herein after does not change much. Relative density of material heated to a temperature of 950 °С for 20–              25 min is 99-100 %. Further increase in heating time leads to a decrease in density after stamping.The value of the hardness of the material correlates with the density. The maximum hardness is 550600 MPa. The value of flexural strength and specific electrical resistivity also correlates with the density of the material, but also depends on the structure of the material. Maximum values of flexural strength is 180200 MPa and minimum values of specific electrical resistance is 3.84.0 mOhm×cm. The results were explained using modern ideas about forming properties of powder materials when their compaction, which enables them to obtain predetermined properties.

Conclusions. Dependence of properties of antifriction materials by electric vehicles (current collector) from the conditions of their manufacture compacting porous hot stamped billets was established. Optimum conditions to obtain materials with maximum density, hardness, ultimate tensile strength and flexural specific minimum electrical output of billets are part blanks heated at the temperatures 900–950 °С for 15–20 min and their following stamping on specific energy of 200–250 N×m/cm3.

Keywords: dispersed-strengthened copper; current collector; density; hardness; flexural strength; specific electrical resistivity; heating; stamping; structure.

Passive Methods of Coherent Vortical Structures Control in Vortex Chambers. Part 1. Spectral Evaluation of Efficiency / Turick V.M., Kochin V.O. - K.: Naukovi visti NTUU “КPІ”. – 2015. – N 6

Background. Investigation of the limited flow structure and possibilities of its control in vortex chambers as elements of power units and manufacturing machinery for its working processes optimal setting.

Objective. The quest of more perfect methods of control by energy carrying coherent vortical structures (ECVS) that have essential influence on processes of mass, momentum and energy transfer in swirling flows and therefore determine the efficiency of installation work.

Methods. The frequency-spatial regions of ECVS, in which the correct statistical analysis of directed actions on its by artificial disturbing eddy formations is possible, are determined by means of visualization and hot-wire measuring of kinematic characteristics of wall current in the test vortex chamber. The disturbing eddy formations are generated in rectangular groove or in three hemispherical dimples of defined dimensions which are built directly in intake nozzle of chamber with adherence to necessary conditions of mutual susceptibility of vortical structures. Numerical processing of measured signals was carried out by fast Fourier transform algorithm.

Results. Small by energy controlling actions to input flow cause substantial rise of power spectral density of velocity fluctuations on the most energy carrying frequencies – approximately in 2–11.5 times depending on eddy-generator type and frequency band, including the “transfer” of energy density to the most large-scale eddy components of ECVS. This fact detects in ECVS all signs of typical open nonlinear dynamical system: existence of resonant modes with sharpening, when the energy feed from controlling vortices and its equiphase perception by Görtler-Ludwieg vortices take place not on full mode spectrum, but selectivity, only for certain harmonic components.

Conclusions. It has been proved experimentally the possibility of effective and low-powered control by macro- and microstructure of swirling flows. It opens the perspective of elaboration of new in principle methods for intensification of the transportable substances transfer in cylinders of internal-combustion engines, in vortex burners, combustors, chambers of rocket engines, furnaces, plasmatrons, mixers, chemical reactors, nuclear power plants etc.

Keywords: coherent vortical structures; control; vortex chamber; hot-wire measurements; probability density  distribution; vortices mutual susceptibility; power spectral density of velocity fluctuations.     

Maximal Range of Vision Thermovision’s Objective Design / Kolobrodov V.G., Gordienko V.I., Mykytenko V.I., Chernyak S.I. - K.: Naukovi visti NTUU “КPІ”. – 2015. – N 6

Background. The work’s background lies in the thermal imaging surveillance systems (TISS) and their input blocks analysis and synthesis.

Objective. Objective of the study is to develop a calculation method for TISS input block design, based on the assumption of specified maximum range of observation.

Method. The application of the linear systems theory to the TISS basic mathematical model, which considers basic components of signal transformation process from object to observer.

Results. A simplified method for the TISS lens synthesis was proposed on the maximum range of observation at given probability of performing visual task criterion. Some approaches from STANAG 4347, which defines TISS nominal ranger performance, were used in the method. The accuracy of calculation algorithms has been proved on the example of calculation of French thermal imaging camera Catherine-FC input unit.

Conclusions. The developed method is compatible with STANAG 4347 and also allows thermal imaging system analysis and matching characteristics of infrared lens and detector.

Keywords: synthesis of a thermal imaging system; surveillance range; infrared lens.

Application of Bispectral Analysis of Vibroacoustic Signals for Blades Cracks Diagnosis in Aircraft Engines / Sopilka Iu.V. - K.: Naukovi visti NTUU “КPІ”. – 2015. – N 6

Background.The work is devoted to vibroacoustical diagnosis of the crack-like damages of the gas-turbine engines (GTE) blades at the steady-state modes of GTE.

Objective.The effectiveness of the usage bispectrum analysis is investigated for signal processing at the vibroacoustical diagnostic of the blades cracks of aviation gas-turbine engines.

Methods.Bispectral analysis is used for diagnostic information processing. Bispectrum can be found using Fourier transform third-order autocorrelation functions:

Results.Simulation bispectrum analysis vibroacoustical signals, radiated by models blades of working wheels without crack and with crack at the stationary vibrating excitations are carried out and investigated. It demonstrates that appearence and evolution of the fatigue crack in a blade increases intensity of bispectral modules.

Conclusions. Application of a modern signal processing methods allows to detect fault features, which are sensitive to small crack-like damages. The receive results can be used to create a vibroacoustical monitoring system for aircraft engine rotor components.

Keywords:signal processing; vibroacoustical diagnosis; gas-turbine engine; crack-like damage.     

Obtaining of Straw Pulp in Isobutanol Medium / Barbash V.A., Yaschenko O.V. - K.: Naukovi visti NTUU “КPІ”. – 2015. – N 6

Background. Decreasing of wood consumption and hazardous wastes in environment due to ecologically safe methods of plant raw material delignification.

Objective. Identification of technological parameters influence on obtaining of organosolvent straw pulp and impact of catalysts (anthraquinone and hydrazine) on the delignification process, main quality indices of pulp, kinetic characteristics.

Methods. Pulping of organosolvent straw pulp with using of catalysts was performed in 0.25 dm3 steel autoclaves placed in glycerol bath heated at temperature 140–180 °C and 30–150 minutes duration.

Results. Obtained organosolvent straw pulp with anthraquinone and hydrazine catalysts are characterized by such physical and mechanical properties: breaking length – 7900–6900 m; burst index – 4.33–4.52 kN/g; folding strength – 128–600 double folds. It was established that using of hydrazine catalyst allows obtaining pulp with lesser lignin, ash and pentosans content then with anthraquinone. It was determined that delignification in isobutanol–KOH–water–catalyst system is described by second-order kinetic equation. Kinetic characteristics (reaction rate and energy of activation) of wheat straw delignification and characteristics of lignin removal from plant raw material were calculated.

Conclusions. Obtained organosolvent straw pulp is suitable for production of paper and cardboard products and after bleaching and alkali treatment – for further chemical treatment into different cellulose derivatives.

Keywords: wheat straw; cellulose; isobutanol; anthraquinone; hydrazine; kinetic characteristics; selectivity indices.

The Metal Oxides Fillers Properties Impact on the Dynamic Mechanical Characteristics of Composites, Cured in Constant Physical Fields / Vilensky V.O., Bardadym Y.V., Tkalіch M.G. - K.: Naukovi visti NTUU “КPІ”. – 2015. – N 6

Background. The latest development in the field of materials to improve the physical and chemical properties is the use of physical modification of polymeric materials. Special attention attracts treatment of external constant magnetic or electric fields of polymeric materials during curing.

Objective.To determine the effects of different natural properties of metal oxides on dynamic mechanical properties of mezocomposites.

Methods. By dynamic mechanical analysis methodstudyof mezocomposite samples filled with oxides of metals, cured by the action of physical fieldswas conducted.

Results. Orientation influence of physical fields changes continuum of molecules involved in the reaction of polyaddition and in the formation of epoxy polymer structure, and leads to the growth of its free volume.  Acquiredelasticity modulus difference is stored in the temperature range of 293–340 K, and when the temperature increases, due to the transition to highly polyepoxy state, the orientation influences of physical fields are lost. Samples were formed under the influence of physical fields are characterized by much higherelasticity modulus values compared with samples formed under normal conditions. Temperature dependence modules losses of epoxy polymer and composites filled with oxides of metals cured under different conditions coincide.

Conclusions. Rationality involvement of acid-base properties to crystal structure aimed modification, thermophysical, dielectric and dynamic mechanical properties of mezocomposites is shown.

Keywords: metal oxide; polyepoxy; physical fields; mezocomposite.

The Efficiency of Coagulation Treatment Wastewater by Reagent Obtained from Waste Alumina Production / Kyrii S.O., Kosogina I.V., Astrelin I.M., Kyrienko O.Yu. - K.: Naukovi visti NTUU “КPІ”. – 2015. – N 6

Background. The accumulation of industrial waste is one of the most urgent problems. So, development of complex technology utilization of wastes (red mud) is most economically and environmentally attractive way to solve the problem of red mud accumulation and getting of highly efficient purification reagents that was obtained from secondary raw materials.

Objective. The synthesis of coagulation reagents of water purification by acid activation of waste alumina production and test possibility of reagents using in wastewater treatment technology from the organic component.

Methods. Photometric analysis methods of initial components and products of coagulation cleaning.

Results. It is found that rational conditions of the red mud processing are: acid activation temperature from 150 to 250 °C; weight ratio of acid to red mud 0.5–2; process duration from 30 to 60 minutes. The high coagulation properties of reagents that was synthesized from waste was established and it was confirmed a high efficiency (82–96 %) treatment of wastewater that was contaminated with organic dyes and surfactants.

Conclusions. It was established that all synthesized samples of coagulation reagents from industrial wastes (red mud and hydrolytic sulfuric acid) are effective coagulants and can be used in water purification technology. Thus, when the “Bright-blue HF” dye concentration in the water 10 mg/l, cleaning efficiency was 96 % at the dose of coagulation reagent 200 mg/l.

Keywords: red mud; acid activation; coagulation; dyes; surfactants; coagulation reagent; wastewater.               

The Modification of Carbon Nanospheres with Oxygen-Containing Groups by the Oxidation in Nitric Acid / Kyrpach K.O., Polunkin Ye.V. - K.: Naukovi visti NTUU “КPІ”. – 2015. – N 6

Background. Purification and functionalization of carbon nanomaterials is an important task to get nanoparticles with a narrow size distribution which will be soluble in organic substrates that allow effectively find practical using of these nanoobjects.

Objective. Specifying of the influence of nitric acid oxidation of carbon nanospheres on their structure and chemical composition.

Methods. The oxidation of the initial samples at 120 °C in solutions of nitric acid of different concentrations was carried out to estimate structural changes. Structural changes and chemical composition were evaluated according to Raman spectroscopy and infrared spectroscopy.

Results. For the first time it is presented the changes in the structure and chemical composition of the oxidized in nitric acid, which was selected as a relatively mild oxidizer, the samples of carbon nanospheres obtained by the high-frequency arc-discharge synthesis using both cyclohexane or propane-butane. The carbon nanospheres’ sizes are about 5 to 50 nm, the spheres have multilayer structure. It is found that with increasing the acid concentration from 15 to 60 wt.% oxidized product yield decreases and the percentage of oxygen in samples increases.

Conclusions. Functionalization of carbon nanospheres by oxidation results in nanoparticles with a significant amount of oxygen-containing groups including COOH, C=O, C–O–C, C–OH. It was found that the oxidation of carbon nanospheres with nitric acid leads to a change of their microstructure with increasing interaction between the graphene layers and the formation of “ideally” inserted layers, as revealed from the shift of the bands in the Raman spectra.

Keywords: carbon nanospheres; oxidation; nitric acid; Raman spectroscopy; infrared spectroscopy.

Magnetic Clay Sorbent for the Removal of Dyes from Aqueous Solutions / Makarchuk O.V., Dontsova T.A., Astrelin I.M. - K.: Naukovi visti NTUU “КPІ”. – 2015. – N 6

Background. Saponite is low-cost sorbent and is effective for removal of organic pollutants, dyes, heavy metal ions from water. However, saponite sorbents are not widely used. The saponite particles waste is removed from the solution after sorption process with considerable difficulties due to their high dispersion. To overcome this difficulty clay particles can be magnetized by magnetite, then by simple procedure (magnetic separation) removed from the water.

Objective. The purpose of this article is synthesis magnetically controlled sorbents based on saponite and magnetite (Fe3O4) by different schemes; the characterization of obtained sorbents and determination of their adsorption properties towards dyes; choice of magnetic module design.

Methods. In the paper modern physic-chemical and experimental research methods were used: X-ray fluorescence, X-ray analysis, physical adsorption/desorption of Nitrogen, sorption and magnetic separation process.

Results. It was found that magnetic modification (in an amount of 2 % magnetite by weight) of saponite by impregnation method allows obtaining mesoporous sorbents with good sorption and magnetic properties. The detected adsorption capacity of magnetically sorbents for all types of dyes (anionic, cationic and nonionic) was 1.5–2.5 times bigger than that for native saponite.

Conclusions. It is shown that modification of saponite by magnetite not only improves its magnetic properties, but also increases its absorption characteristics (specific surface area, sorption capacity). The impregnation method allows obtaining magnetic clay sorbent with better sorption and magnetic characteristics. The pyramid magnetic module was the most effective magnetic module design for deposition of spent magnetic sorbent.

Keywords: saponite; magnetite; dyes; magnetic clay sorbent; adsorption; magnetic separation.

Inhibition of Microbial Corrosion, Caused by Sulfate-Reducing Bacteria, by Heterocyclic Amines and Substances, Composed on Their Basis / Pogrebova I.S., Kozlova I.P., Purish L.M., Sokolovs’ka M.V. - K.: Naukovi visti NTUU “КPІ”. – 2015. – N 6

Background. Microbial corrosion, caused by sulfate-reducing bacteria (SRB), is one of the dangerous kinds of iron and steeldestruction. However, today there are only a small number of compounds, which are used as inhibitors of microbial corrosion are known.

Objective.The objective is to study the effect of nitrogen-containing heterocyclic compounds and their combination with the metal salts in the carbon steel corrosion in salt solution containing SRB and determination of mechanisms of their protective action.

Methods. Research was carried out with mass-metrical, electrochemical and microbiological methods with carbon steel in chloride salt electrolytes, the culture of “Kiev 10” and organic and inorganic compounds.

Results.The compositions of benzotriazole with calcium and magnesium salts are the most effective in 3 % NaCl solution and quaternary pyridinium salts practically make no influence on corrosion of steel. Protective effect of quaternary pyridinium salts is substantially increased and the degree of protection of steel in anaerobic conditions reaches 98 % at the transition to the inoculated salt solution. It was established that increase of the efficiency is caused by the changing nature of the cathodic reaction of corrosion process, by high antibacterial properties of organic compounds and the synergistic effect of metabolic products of SRB.

Conclusions. Quaternary pyridinium salts and benzotriazole compositions with calcium and magnesium salts demonstrate high protective properties in steel corrosion in salt solutions containing SRB. The degree of protection is achieved by 90–98 %.

Keywords: microbiological corrosion; sulfate-reducing bacteria; polarization resistance; carbon steel; quaternary pyridinium salt; benzotriazole; calcium salt; magnesium salt.

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