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Proceedings of the Southwest State University

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Vol 24, No 2 (2020)
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Mechanical engineering and machine science

8-16 464
Abstract

Purpose of reseach was to evaluate the dimensional characteristics of powders obtained by electrodispersion of high-chromium corrosion-resistant steel in lighting kerosene.
Methods. When setting up experiments for electroerosive dispersion, wastes of high-chromium corrosion-resistant steel X17 were selected. Dispersing equipment - experimental setup (RF Patent No. 2449859). Lighting kerosene was used as a working fluid. In order to stabilize the process, the dispersion modes were selected experimentally and were as follows: voltage 100 V; pulse repetition rate 120 Hz; capacity 48 μF. The granulometric composition of the powders was studied using a laser particle size analyzer "Analysette 22 NanoTec".
Results. It has been found that the average particle size is 28.66 pm and 95% of the total volume of particles in the powder have a size less than or equal to 57.36 pm. ,based on the conducted experimental studies aimed at studying the particle size distribution of electroerosive powders obtained from wastes of high-chromium corrosion-resistant steel X17 in lighting kerosene on an experimental setup (RF Patent No. 2449859) at a pulse repetition rate of 120 Hz, a voltage of 100 V and the capacity of the discharge capacitors is 48 μF.
Conclusion. The conducted research will allow us to obtain new powder materials from wastes of high-chromium corrosion-resistant steel X17 in lighting kerosene with a guaranteed particle size distribution, through the use of progressive, environmentally friendly, low-tonnage and waste-free technology of electroerosive dispersion.

17-36 563
Abstract

Purpose of reseach is to study the influence of the quality of the original charge on the complex of physical, mechanical and operational properties of structural low-alloy steel 30HGSA.
Methods. As an object of research, a typical representative of low-alloy structural steels has been chosen - steel 30HGSA, smelted using metallized sponge iron pellets, ordinary scrap metal and billets obtained by the method of a boiling slag layer. In accordance with the set objectives of the study, steel 30HGSA of various melts, obtained with different charge, had the same conditions for melting, evacuation, deoxidation, casting and crystallization. The casting temperature was 1600...1620 оC and the post-vacuum treatment temperature was 1530...1560 °C. Duration of evacuation - 5 minutes. Casting of melts was carried out into cast iron molds with a siphon for 4 ... 5 minutes. Deoxidation was carried out in a ladle with aluminum in the amount of 4 ... 4.5 kg / melt. After solidification, the ingots were cooled in special wells. The ingots were cut into 3 parts: head, middle and bottom (600 × 600 mm). The middle part was then hot forged and rolled to a Ø30 mm bar. The length of the rod was 2 ... 3.4 m. After hot deformation, the rods were cooled in air.
Results. Mechanical tests have been carried out. Statistical processing of experimental results has been performed. Regularities of changes in the characteristics of mechanical properties have been revealed: tensile strength, creep strength, relative narrowing of the cross-sectional area of the sample, relative elongation of the initial working length, impact strength (σВ, σ0.2, ψ, δ, aН).
Conclusion. It has been found that with an increase in temperature, the mechanical properties of steel 30HGSA, smelted on various charges, decrease. It has been established that the cold brittleness threshold of 30HGSA steel is lower for purer melts on spongy iron and intermediate product KShS, the value of impact toughness at low temperatures is higher than in melting on a conventional metallized charge. Noticeable softening begins at a tempering temperature of 300 °C The temperature of the maximum tempering brittleness for steel 30HGSA, melted on a conventional metallized charge, is 550 °C It is shown that steel 30HGSA smelted with a pure original charge (spongy iron) has a lower tendency to temper brittleness than steel smelted with a conventional charge. The value of the impact toughness of the steel of this melt is higher than that of the steel of conventional melting over the entire tempering temperature range.

37-48 406
Abstract

Purpose of research was to plot the amplitude dependence of the decrement of longitudinal and bending vibrations of samples of porous metal composites manufactured using 3D technology.
Methods. The main attention is paid to the role of microplasticity in the scattering of the vibration energy, since the decrement value in composite will be greater than in monolithic material. The effect of porosity on the level of energy dissipation is taken into account. We have used a statistical model based on the results of the theory of functionals given on random processes.
Results. This made it possible to find the concentration of microplastic zones in the composite during longitudinal and bending vibrations of the sample. The value of the vibration decrement is defined as the ratio of the potential energy of plastic deformations to the total potential energy of the entire sample. To calculate the effective moduli in the composite, the well-known technique of the theory of elasticity of micro-inhomogeneous media is used. The results obtained indicate that porosity significantly affects the concentration of microplastic zones and the scattering of internal friction during longitudinal and bending vibrations. However, it should be noted that at low amplitudes, microplastic regions are not formed in the vicinity of the pores. Therefore, the reasons for the appearance of energy dissipation are not explained only by microplasticity. The source of such losses are dislocation, ferromagnetic and other reasons. However, the level of these losses is much less than that indicated in this work, and depends only on the oscillation frequency.
Conclusion. The results obtained can be used to establish the patterns of behavior of various natures of ingot, powder and composite materials with high dispersion in phase and structural components in various conditions and states.

49-59 482
Abstract

Purpose of research is to develop a method for accounting for the influence of end washers on the flow of wings with an arbitrary distribution of fillets over the span.
Methods. The installation of end washers significantly improves the aerodynamics of the wing, increasing lift and reducing inductive resistance. The theory of a continuous vortex surface is applied to simulate the effect of end washers on the flow of a volumetric wing. In accordance with it, oblique horseshoe-shaped vortices that model the upper and lower sides of the wing are continuously distributed along the longitudinal panels, into which the half-span of the wing is divided. The bearing parts of each horseshoe-shaped vortex lie in planes parallel to the plane of the wing chords and pass through the points and the middle section of the panel at which the induced velocities are calculated. The free vortices of the wing descend from its ends from the upper and lower surfaces at an angle to the plane of the chords.
Results. An algorithm has been developed for calculating the intensity of vortices from the non-permeability condition, taking into account the attached and free vortices of the wing and the end-washer vortices. The vortex densities included in this condition are represented by trigonometric series. The developed method takes into account the geometry of the profile and end washers, the shape of the wing in the plan. The vortices induce an additional velocity at the points on the surface of the wing. To calculate their values, the Biot-savard formula on vortex influence is used.
Conclusion. A method for calculating the aerodynamic characteristics of a volumetric wing with end washers has been developed from the unified positions of the theory of a continuous vortex surface. The calculations take into account the geometry of the washers and profile, the shape of the wing in the plan. The method is universal and can be used for wings without washers, including for thin ones.

Constructions

60-72 461
Abstract

Purpose of research. Inspection and assessment of the technical condition of the enclosing structures of a residential building located at st. Engelsa, 107 in Kursk were carried out in connection with the development of the reinforcement project.
Methods. Inspection of the technical condition of buildings and structures is necessary to determine the residual resource and service life of the building structures. The current regulatory documents require an examination of the technical condition of buildings and structures no later than two years after their commissioning. In the future, the inspection of the technical condition of buildings and structures is carried out at least once every 10 years and at least once every five years for buildings and structures or their individual elements operating in adverse conditions (aggressive environments, vibrations, high humidity, seismicity of the area 7 points and more, etc.). A permanent monitoring regime is established for unique buildings and structures.
Results. In the process of examining a residential building located at st. Engelsa, 107, the following tasks have been solved: determination of damage to enclosing structures; analysis of the results of the study of the degree of wear of building structures; implementation of proposals for strengthening the brickwork. To eliminate the above damages, a proposal was developed to increase the rigidity of the above-foundation part of the building, having previously excluded soaking the foundation soil: by repairing the blind area and heating, water supply and sewerage networks.

Conclusion. The solution of a narrow task of strengthening individual structures of buildings and structures may not give the desired result, therefore, when performing inspection work, it is necessary to consider the existing defects and damage in the complex. Within the framework of this work, we consider the strengthening of the load-bearing walls of a residential building with an increase in the overall rigidity of the above-foundation part of the building and the elimination of individual damages.

73-89 497
Abstract

Purpose of research is to carry out an applied research of the thermal behaviour of the production premise of an industrial building and to develop air conditioning processes, including the search for an expedient circuit design for conditioning and increasing the effectiveness of the system by using the cold outdoor air.
Methods. In the work, based on the results of the energy audit, a technique for calculating the flows of harmful emissions in the production premise in the Production mode was developed and the thermal loads of the objects of the study were determined to achieve the set objectives. Possible options for air processing by technological conditioning systems including the minimization of energy costs are analyzed. For the assimilation of excess heat in the warm season and a rational choice of the air treatment process in order to save thermal energy consumption, techniques of air treatment with and without heating are proposed. In the cold season, it is proposed to carry out air conditioning using cold outdoor air. The versatility of the technique makes it possible to determine a process feasible in real conditions, including adjusting the processing scheme, in which air preheating is required.
Results. The result of the research work is the development of a number of engineering and technical solutions to ensure the energy efficiency of the engineering system and improve the consumer quality of the research objects.

Conclusion. Implementation of the developed measures for thermal protection of the research object and the use of energy-efficient engineering solutions will allow achieving the following results: to improve the consumer quality of buildings, to bring the parameters of the internal microclimate to the standard value; to extend significantly the service life of enclosing structures, to ensure the quality of the air intended for the technological process with a high degree of accuracy, to ensure energy savings for air conditioning through the use of the cold outdoor air; to maintain a minimum cooling temperature by mixing outdoor and recirculated air without the risk of frost formation on the surface of the heat exchanger and the formation of ice.

Computer science, computer engineering and IT managment

90-107 424
Abstract

Purpose of research is to apply the modified Ward method in high-speed processing of full-size images of Earth remote sensing.
Methods. The classical Ward method is modified by dividing the computational process into three successive stages. At the first stage, a rough hierarchy of approximations is built. At the second stage, an intermediate improvement of the quality of the given partition is performed for a fixed number of colours. At the third stage, the obtained superpixels are clustered using the classical Ward method. The software-algorithmic toolkit consists of four operations on pixel clusters and image segments: merging a pair of clusters into one, dividing a cluster into two original ones, singling out a subset of pixels into a separate cluster and reclassifying some pixels by excluding them from one cluster and assigning them to another. The quality is assessed by the total squared error. Improving the image decomposition quality is ensured by iterative execution of a combination of merging and deviding pixel clusters, image segments, in particular. One of the clusters (segments) is devided in two and a couple of others non-coincident with it are combined into one according to the criterion of minimum increment of the total squared error.
Results. The proposed modified Ward method is applied in the processing of full-size images of Earth remote sensing taken from the database of the USC Signal and Image Processing Institute. The results of processing in the modes of pure segmentation and clustering are compared.
Conclusion. The proposed pixel clustering model is suitable for high-speed processing of full-size images. Pixel clustering in comparison with image segmentation makes it possible to define in more detail both the contours of objects of interest and their internal structure.

108-121 543
Abstract

Purpose of research is to build a model of a system for effective authentication of mobile users based on public data of the user and his behavioral factors as well as to study algorithms for calculating the threshold value at which the authentication of a mobile device user is considered successful.
Methods. When analyzing the behavioral factors of a user who needs to be authenticated when interacting with mobile devices, application of the following methods for calculating the threshold value are proposed: dynamic methods for determining the threshold value of user authentication based on the standard deviation and the calculation of the aggregate mean score; the method based on the standard when the system divides the aggregate flow of estimates into several blocks of the same length, where the first block is used for training, and the calculated threshold is used in the second block (this sequence of actions is repeated continuously, that is, the previous block provides training results for calculating the threshold for the current block); a method for calculating the aggregate mean score, where instead of using a single total score as input, the system uses the mean value of the current block, and the new calculated threshold is used as the threshold for decision making for the next block. A mathematical model that balances the speed and reliability of mobile users authentication is proposed.
Results. The result of the research is the development of an effective system for calculating the threshold value of successful authentication of a mobile device user based on behavioural features which adapts to changes of the user's behavioural factors. Experimental studies and comparisons with analogs confirming the completeness and correctness were carried out as well as various variants of the proposed solutions.
Conclusion. The proposed method of implicit authentication for mobile access control is easy to implement, easy to use, and adaptive to changes in input data. Options for calculating the threshold value at which implicit authentication is considered successful are also proposed.

 

122-135 463
Abstract

Purpose of research is to develop a conceptual structure for managing the customer database of the insurance company based on the integration of models of data mining and system dynamics. The implementation of the conceptual structure involves clustering the customer database, modelling the dynamics of the customer database and developing strategic goals for each segment of the customer database in order to increase customer lifetime value.

Methods. The article presents a theory-multiple model of the insurance company activity in the context of customer relationship management, which made it possible to determine the logical structure, system relationships as well as a set of functions performed within this process.
Results. The proposed conceptual structure of the customer relationship management system includes tools for analyzing key indicators of the customer database, segmenting the database using several clustering methods and structuring by indicators of customer's profitability, satisfaction with insurance services as well as strategizing sales development for each customer segment, which includes the formation of management decisions in the form of marketing activities, optimizing costs and expenses in promoting services on the market due to rational and competent positioning.
Conclusion. Based on the task set, an algorithm that allows analyzing the customer database by key indicators, segmenting, structuring customers and forming sales development strategies of the insurance company aimed not only at retaining existing customers but also at increasing the value of each one by increasing customer lifetime value and increasing sales for each cluster as well as increasing the volume of insurance premiums by attracting new customers is proposed.

136-152 581
Abstract

Purpose of research. The article is devoted to the issue of ensuring the safe transmission of control signals between the elements of a multi-agent robotic system. The purpose of the work is to provide hidden data transmission with the possibility of unambiguous extraction of control signals.
Methods. To solve the task set, an algorithm based on the methods of digital watermarks and digital steganography was proposed. The method of forming a digital watermark in the form of a ring with symmetry allows not only ensuring maximum imperceptibility of embedding (insignificant distortion of the container during concealment), but also to protect the transmitted signal from such complex distortions as image rotation. The steganographic concealment method allows regulating the intensity of embedding using the force factor; it is computationally simple and straightforward. The proposed approach to identifying and understanding the transmitted signal differs from modern methods of cryptography and steganalysis in that it does not require 100% correct signal extraction. After several modifications, the method allows minimizing the time spent on formation (adaptive width of the ring with signal bits) and embedding of a digital watermark (minimization of the processed area of the container for embedding).
Results. The proposed approach makes it possible to transmit control signals in a hidden way within the framework of the transmission of digital objects; the conducted experiments have shown that the control signal is unambiguously understood even with such distortions as a decrease or increase in contrast or brightness, image rotation, and compression.
Conclusion. Application of the proposed technique for transmitting control signals in a multi-agent robotic system will male it possible to receive the necessary information timely and safe, with a minimum probability of loss.

153-169 520
Abstract

Purpose of research is to develop a method for arraging routes for elimination of spontaneously formed unauthorized dumps on the territory of a municipal formation of a constituent entity of the Russian Federation.
Methods. The development of a method for arraging routes for elimination of unauthorized dumps is based on the theory of graphs, which includes algorithms for finding the shortest path: Dijkstra's algorithm, Floyd-Warshall algorithm, Ford-Bellman algorithm, Hamiltonian cycle, etc. Having analyzed the peculiarities of using the listed algorithms, the authors have developed a method for arranging a route for the elimination of unauthorized dumps based on the Hamiltonian cycle.
Results. The task of arranging a route is reduced to choosing those unauthorized dumps from the detected ones, which will be accepted as the vertices of the graph, between which it is necessary to find the shortest path. The authors' approach to the formation of a set of vertices of the graph is as follows. At the first stage, the initial and boundary conditions are set. The parking of special equipment (garbage trucks) is selected as the zero vertex of the graph, and the SMW polygon is selected as the last (nth) vertex. In this case, it should be taken in the account that after transporting waste from dumps to the place of their burial (landfill), the garbage truck must return back to the parking place. The limits taken into consideration are the maximum distance that the garbage truck can travel without refueling and the volume of the garbage truck body. Then, the closest to the starting point unauthorized dump which represents the greatest danger to the environment is chosen as the first vertex of the graph. An unauthorized dump closest to the first peak is chosen as the second, etc.. The search for vertices continues until the inequalities that take into account the given constraints are satisfied. Next, a graph, an adjacency matrix, and a route are formed. With this approach, for arranging a route, it is optimal to use the Hamiltonian cycle, which ensures finding the minimum path between all the vertices of the graph and returns to the starting point.
Conclusion. Application of the authors' method for arranging routes for elimination of unauthorized dumps will make it possible to promptly clean up unauthorized dumps found in the city, which will significantly reduce the environmental load.



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ISSN 2223-1560 (Print)
ISSN 2686-6757 (Online)