The article deals with the case when a concentrated force is applied to the web of a prestressed beam. The preliminary shear stresses do not affect the stress state in the middle of the beam span. However, preliminary normal stresses will act over the entire height of the wall and affect the distribution of the zone of local stresses and the stress state of the web. Determination of stresses in a beam is based on the beam theory of S.P. Timoshenko. The article presents a system of equivalent forces on the edges of the wall and the equation of normal stresses in the cross section of a prestressed beam. Compared to a conventional beam, prestressing reduces normal stresses from concentrated forces.

Keywords: thin-walled structure, steel beam, I-beam cross-section, prestressing, local stresses, local effect, Saint-Venant principle, Timoshenko SP beam theory, Karman's solution, Fourier integral, stress function

In the automation of production, the use of robots is an important direction. When developing algorithms for controlling the movement of such a machine, multidirectional problems arise. In a critical situation, the robot must not harm workers or collide with its fellow robot. At the same time, the car must move along the optimal route. The article analyzes the methods of finding optimal paths on square navigation grids. The wave method on undirected planar graphs, the A* algorithm (an extension of Dijkstra's algorithm), and the D* Lite algorithm for graphs with non-constant or previously unknown structure were chosen for the analysis. A visualization and testing system in C#has been developed for the research and testing of algorithms. The system is implemented using the Microsoft Visual Studio 2019 IDE software tools and external GraphX and Emgu CV libraries. A unique feature of the system is the ability to directly read images of shop floor maps in widely used graphic formats and automatically convert them to a format that is understandable to the system. First, the user uploads the shop floor plan. For easier processing, the image is converted to two colors: black and white. Then the image is processed by the Emgu CV library, at the output we get all the contours of stationary obstacles. Then, depending on the size of the robot, an orthogonal navigation grid is superimposed. The analysis of the obtained results allows us to conclude that it is better to use a method (the D* Lite algorithm) that allows for a non-constant or unknown grid structure in advance.

Keywords: visualization, program, graphic format, work, shop, map, square, grid, cell, navigation, optimal route, planar graph

The article provides an assessment of the economic efficiency of a prestressed bistal beam, prestressed stretching of web. The comparison is made with a conventional bistal girder without prestressing with the same cross-section. The costs of material, design, production, transportation and installation are considered. It is taken into account that to create pre-stress, more labor costs are always needed, therefore, the manufacture of pre-stressed structures is more expensive than conventional structures. The purpose of prestressing is to reduce the consumption of steel in the fabrication of the structure. The structure of labor costs for the manufacture of structures is given. A comparative analysis of the cost "in business" of a running meter of a beam, prestressed by wall stretching, and a beam without prestressing, depending on the complexity of their manufacture, is carried out.

Keywords: thin-walled structure, bistal girder, I-beam, prestressing, stretching of web, structure weight, overhead costs, labor intensity of manufacture, cost-effectiveness, custom design, value in action

This article provides information on the possibility of using offshore wind farms to provide energy to offshore structures such as oil and gas platforms, as well as coastal communities.

Keywords: wind power plant, wind generator, offshore power plant, SIEMENS generator, offshore oil and gas facility, oil and gas field, coastal settlement

Crushed stone-mastic asphalt concrete is a more durable material compared to traditional asphalt concrete. But for its exploitation, high-quality mineral powders and bituminous carriers are needed to prevent bitumen from flowing out of the composition. Today, the carbonate rock powders and bituminous carriers from natural cellulosic fibers are widely used. However, many Russian Federation regions, including the Krasnoyarsk Territory, are not provided with these materials, and they are also really expensive. The purpose of our work was to reduce the cost and improve the properties of crushed stone-mastic asphalt concrete. The task of the research was to develop gravel-mastic asphalt concrete compositions using the industrial waste from the Krasnoyarsk Territory. Nepheline sludge was tested which is the waste of the alumina plant in Achinsk and rubber crumb with inclusions of cord fiber of Chernogorsk in Krasnoyarsk Territory. The chemical composition and physical and mechanical properties of these wastes were studied. Gravel-mastic asphalt concrete compositions were made by using these wastes. The tests showed that the received compositions met regulatory requirements. The developed compositions were introduced by “Krasnoyarskavtodorom” on the Krasnoyarsk Territory roads. The economic effect of the waste usage is achieved through the exploitation of the local raw materials, which leads to a reduction of the transportation and energy costs.

Keywords: the crushed stone-mastic asphalt concrete, industrial waste, nepheline sludge, mineral powder, bituminant, rubber waste with corded fiber inclusions, crushed stone, sand Crushed stone-mastic asphalt concrete, industrial waste, nepheline sludge

The article analyzes the results of experimental studies of prestressed steel I-beams. Presented specific features of the stressed and deformed states of welded steel beams, prestressed by wall stretching and bending of the initial T-element. In the first method, the prestressing in the beam was created by mechanical stretching of the wall on a special stand. In the second method, the T-piece is loaded by external forces applied to the T-bar plate until normal stresses appear at the bottom point of the wall, equal to the design resistance of low-carbon steel, then the second belt plate is welded to the T-piece element. The results of a numerical experiment with these beams, carried out in the SP LIRA, are considered. Presented a comparative assessment of the results of numerical and full-scale tests of prestressed I-beams a similar section with bimetallic beams without prestressing.

Keywords: web stretching, T-beam bending, section asymmetry, numerical experiment, test stand, stress, bearing capacity, beam rigidity, bending deformation, local stability

Blasting operations are often the only way to prepare the material for the recess for laying roads and railways in the rocks. Explosive loosening is also used to extract stone as a building material. Field testing is costly and often dangerous. Therefore, it is necessary to first conduct a series of experiments on the model and find out the conditions for ensuring good quality loosening of rocks. In order for the results of model tests to be transferred to nature, a similarity between model and specimen is required. The approximate similarity is achieved by the equality of the similarity criteria for the model and specimen. The characteristic similarity criteria are obtained by analyzing the physical quantities inherent in a mechanical system using the theory of dimension and similarity. The received criteria are presented in the classical form. These are the criteria of Strouhal, Froude, Cauchy and Newton.

Keywords: explosive loosening, rock material, deceleration interval, similarity criterion, modeling, rock density, model, specimen, expansion height, dimensionality, physical quantity

The process of finding the calculated lengths of the elements of a cross lattice using the displacement method in the case when both bars are not interrupted and when one of the bars is interrupted and overlapped by a gusset is considered. New formulas of the displacement method are proposed for finding the support reactions of an element having a spring fixation at one of the ends. A formula is proposed that allows you to determine the spring stiffness, with the help of which the operation of the connecting strip is simulated. A comparison is made of two calculation options: using the usual formulas of the displacement method and using the proposed new formulas. The calculation showed good convergence of the results with a significant simplification of the calculation process in the second case. A comparison of the calculated lengths obtained with the instructions of the current sets of rules is given. The possibility of adopting a more economical section when determining the calculated length by means of the displacement method is noted.

Keywords: estimated length, cross lattice, stability, critical force, truss

The presented article describes the modeling of a communication system (hereinafter SS) organized by a plurality of communication nodes of a public communication network (hereinafter SS SSN) and its elements. The task of modeling is to obtain interrelated initial data on the set of features for each investigated SS of the SSNS at each moment of the model time, taking into account the implemented activation processes and the logic of SS functioning. The process of functioning with the SS as a source of features is studied using a complex analytical and simulation model, since deterministic and random factors are taken into account for its development. The manifestation of signs is a complex process, since the SS is constantly in dynamics. However, the increasing intensity of the increase in the use of communication means and the load in communication channels leads to an increase in the number of manifested set of signs. The reasons for the manifestation of many signs are such factors as: dynamics of movement of the USS of the SSOP; modes of operation of SSOP elements, etc. All of these factors are used in the model as activating the manifestation of many features.

Keywords: communication system, public communication network, communication node, sign of a system element, information direction, activating factor

At present, the number of means for collecting information about the characteristics of elements of a public communication system is increasing. Databases.

Keywords: database, monitoring systems, information, resolution, processing of information arrays, similarity rate, process automation, public communication system, communication system elements

The article deals with the issue of improving the quality of the food chopper. Both domestic and industrial shredders are considered. Engineering solutions are proposed that will reduce the operating costs of the consumer and increase the energy efficiency of the grinding process. These recommendations have been tested in production and are reliable.

Keywords: quality, chopper, energy efficiency, blade, gap, angle, knife, grate, operation, production

Permafrost occupies about 25 percent of the world's area and spreads across the north of America, Europe, Asia, as well as the islands of the Arctic Ocean and Antarctica. In Russia, a considerable part of the population lives and works in the regions of the Far North, where mining is rapidly developing in conditions of permafrost. This is where the erection of the foundations is an important issue.

Keywords: pile foundations, permafrost, drilling, oil production, land, territory, deformations, soil, installation, screw piles

The article is devoted to the possibility of applying the methods of successive approximations in the analysis of the instantaneous scheme of the traction network. The described approach allows to improve the accuracy of modeling dynamic modes of operation of traction power supply sections, and also allows to significantly improve the process of modeling diagnostics and control systems of electric rolling stock at the design stage based on a more accurate model of dynamically changing input parameters of the traction network, depending on their required level.

Keywords: traction network, instantaneous circuit, diagnostics, simulation, recruitment model

The paper is focused on research of an access control system based on the analysis of the thermal radiation of the user's palms using common components, it is shown that the use of multifactor biometric authentication based on the thermal image of the palms and infrared images of the user's veins allows to reduce the errors of the first and second kind during biometric authentication.

Keywords: biometric authentication, thermal palm print, access control system, infrared vein imaging

The article considered the propagation of a long impulse signal in a hydroacoustic waveguide. A solution is given for a replica of a impulse signal in the second approximation of the dispersion theory. The propagation of a single-mode and multimode impulse in a Pekeris waveguide with a bottom in the form of an absorbing half-space is simulated. The acoustic properties of the half-space correspond to medium sand with an average grain size 0,3 mm. The result of the solution in the second approximation of the dispersion theory is compared with the result of the simulation of the impulse replica obtained as a convolution of the input signal with the impulse response of the waveguide. The disadvantages of the solution in the second approximation of the dispersion theory are shown and analyzed. It is shown that the theory of dispersion incorrectly reproduces the transients when the signal is switched on and off in cases where the signal frequency lies near the critical frequency of the first or second mode. It is shown that the theory of dispersion correctly reproduces the envelope of a multimode impulse signal.

Keywords: impulse signal, normal modes, group velocity, dispersion theory, intramode dispersion, intermode dispersion