In present work, methods of in situ regeneration for the Co-Al2O3/SiO2 catalyst were studied. The activity and selectivity of the catalyst in the Fischer-Tropsch synthesis are shown, as well as the compositions of the products in different periods of its operation. Process parameters after regeneration regimes and before stabilization of catalyst activity were studied. The compositions of the products of the Fischer-Tropsch synthesis after the renovation of the catalyst are analyzed and compared with the initial ones.
Keywords: Fischer-Tropsch synthesis, heterogeneous catalysis, catalyst regeneration, synthetic hydrocarbons
The article is devoted to the analysis of the spatial structure of acoustic pressure and particle velocity fields in hydroacoustic waveguides of the sea shelf. Waveguides with two types of sound velocity profile are considered: constant and having an underwater sound channel. The bottom is assumed to be a transitional layer with a sound velocity gradient and a half-space. The acoustic properties of the layer are assumed to be those of silt or sand. The interference structure of the pressure field and the field of the vertical component of the particle velocity is analyzed. The spatial laws of attenuation pressure and particle velocity fields are analyzed. It is shown that the interference structure and the laws of decrease of the pressure field and the vertical component of the particle velocity do not coincide. The article is devoted to the analysis of the spatial structure of acoustic pressure and particle velocity fields in hydroacoustic waveguides of the sea shelf. Waveguides with two types of sound velocity profile are considered: constant and having an underwater sound channel. The bottom is assumed to be a transitional layer with a sound velocity gradient and a half-space. The acoustic properties of the layer are assumed to be those of silt or sand. The interference structure of the pressure field and the field of the vertical component of the particle velocity is analyzed. The spatial laws of attenuation pressure and particle velocity fields are analyzed. It is shown that the interference structure and the laws of decrease of the pressure field and the vertical component of the particle velocity do not coincide.
Keywords: normal modes, particle velocity, seabed, interference structure, incoherent addition
The operability of an optical device depends entirely on the quality of the optical parts that make up the optical system. Timely measurement of errors of optical parts in the process of surface shaping organizes feedback: the more accurately the error is measured, the more accurately the correction of the geometry of the surface is possible. Errors of optical surfaces and optical systems in general can be estimated by the mismatch of coordinates of real and ideal (calculated) profile curves of surfaces; mismatch of normals to this surface; difference of wave fronts in incident and refracted (or reflected) beams of light rays, etc.. The reproducibility of optical surfaces from sample to sample and their compliance with the calculated one is usually estimated by the discrepancy between the actual and theoretical functions of the course of light rays. Such a discrepancy is estimated by the aberrograms of optical systems, which are determined experimentally on special installations – aberrographs. Unlike the known schemes for measuring longitudinal aberrations of only reflectors or only lenses, the devel-oped installation is universal, designed to measure zonal aberrations of large-diameter mirror and lens lenses that are used in lighting devices, solar energy concentrators, transmitting and receiving optical systems of optoelectronic de-vices.
Keywords: aberrometer, aberrogram, longitudinal aberration, lens lens, mirror lens
A variant of the mathematical model of the problem of optimal cutting of a semi-infinite strip of material with the possibility of rotating the workpieces by 90 degrees is proposed. Two-dimensional blanks close to the shape of a rectangle or inscribed in a rectangle are considered. The process of recalculation of the basic sizes of blanks has been formalized. It is shown that the increments of the length and width of a rectangular blank can be determined in various ways. The developed mathematical models are mainly focused on solving the problems of small enterprises and the production of simple-shaped products. Recommendations on the software implementation of the cutting model are given.
Keywords: mathematical model, optimization, optimal cutting of a semi-infinite strip, rectangular workpieces, recalculation of the sizes of workpieces, rotation of workpieces by 90 degrees
This article proposes a method for determining the emotional state of a person using a chatbot. The article defines a chat bot, justifies the choice of the type of chat bot, and defines the basic principles of their work. Based on the identified differences in the work of algorithms for determining text by chat bots, the most suitable technology for solving the task is described - working with neural networks.
Keywords: chatbot, neural network, text tone, emotions, augmented reality
A computer simulator for training operators of the technological process of granulating ammophos in a drum granulator dryer is considered. The technological object and the requirements for controlling the granulation process are briefly described. The functions of the simulator, the structure of its mathematical and algorithmic support are given. The software implementation of the simulator is made in the Visual Basic environment.
Keywords: computer simulator, mathematical model, algorithmic support, training of process operators, pelletizing, drum granulator dryer, granule diameter, ammophos pulp
The study of the problem of fretting damage to a mechanical assembly bolted in three dimensions requires the analysis of stress fields in Cartesian coordinates along the angle and radius of contact pads. It also requires determining the location of the crack initiation and propagation. In this study, we will focus on numerical simulation using ANSYS. The results obtained in the form of nodal solutions show in detail the positions of stress concentrations and the formation of the bolted assembly. The contact surface between plates (or contact elements) is characterized by contact pressure, adhesion and clearance. The results obtained made it possible to determine the stress that caused the initiation and propagation of a crack, as well as the position of the damaged area by fretting.
Keywords: bolt assembly, contact modeling, damage zone, fretting, Ramberg-Osgood law, Von Mises stresses
In this paper, the results of modeling the system "vibrating roller - compacted asphalt concrete" are considered. The analysis of the state of the quality of compaction of asphalt concrete mixture by the method of continuous control of compaction of asphalt concrete, as well as the influence of the behavior of the fluctuating mass of the roller on the viscosity properties of asphalt concrete is given. A mathematical model has been developed that allows taking into account the influence of asphalt concrete properties changing during the compaction process on the vibration characteristics of the vibrating roller. The spectrum of accelerations of the vibrating roller and the graph of the dependence of the stress of the asphalt concrete mixture in the compaction process are obtained. The developed model makes it possible to determine changes in the properties of the compacted material and the nature of vibrations of the vibrating roller. It is determined that with an increase in the value of the stiffness coefficient of asphalt concrete, the acceleration spectra of the vibrating roller also change. When the vibrating roller is in constant contact with the surface, only the harmonic at the operating frequency of the vibrating roller is visible on the acceleration spectrum, without the manifestation of other harmonics and subharmonics.
Keywords: vibration roller, asphalt concrete, material compaction, dynamic model, vibration characteristics, acceleration spectrum
The article presents the results of the study of the ventilation device. A system of automatic control of the process of regulating air exchange in a residential area has been developed, which allows you to control an element of the actuator, which increases the productivity and efficiency of the ventilation device. An automated module of the process of regulating air exchange in residential buildings has been developed, designed to control the regulation of air exchange and its determination in residential buildings in different periods of the year. The software module implements recalculation of the main heat and humidity parameters of the air.
Keywords: air exchange, automated module, automatic control, ventilation device
The paper is focused on the building heightening technologies employing modular structures, and in particular, three-dimensional units. It lists the global leaders in the field of manufacturing of three-dimensional/modular units and examines the work stages based on the analysis of scientific publications and patent searches. It is noted that the process arrangement upgraded to the current state of the art and the improved energy efficiency performance of a superstructure are mainly achieved through the use of modular units with greater dimensions but with a lighter weight.
Keywords: reconstruction, technology, energy efficiency, superstructure, modular constructions, volume blocks, organizational and technological solutions
This paper is a follow-up on the first part, which also reviews the process arrangement solutions for building reconstruction based on building heightening using modular structures. It highlights the importance of the use of transformer (stacked) modules, which allows improving the work process flexibility at the installation and transportation stages. It is further specified that, if reconstruction is carried out in congested urban environments, three-dimensional/modular units should be prefabricated, as prefabrication helps to significantly reduce a gap between the actual and standardized work timelines, even in case of force majeure.
Keywords: superstructure, organizational and technological solutions, transforming three-dimensional blocks, assembly and transport manufacturability
Alternative approaches to estimating the stiffness of corrosion-damaged beams taking into account localization of corrosion focus and corrosion damage development of concrete based on the model of V.M. Bondarenko are considered. The following methods of determining displacements of corroded reinforced concrete beams of rectangular cross-section are considered. In the first one, the stiffness of the beam in determining the deflection is considered to be constant. In this case, the corrosion-damaged deflections values may be underestimated due to failure to take into account the actual work of reinforced concrete. In the second, the deflection is calculated considering the height of the concrete compression zone that varies along the length of the beam. For these approaches, stiffness reduction in the beam sections in the presence of corrosion damage to the concrete of the compressed zone is modeled. It is shown that in the presence of corrosion damage, the deflections of the structure can significantly increase, which requires mandatory consideration in the life cycle of load-bearing structures of structures when assessing their mechanical safety.
Keywords: reinforced concrete beams, strength of reinforced concrete elements, bending stiffness, deformability, corrosion damage of concrete, height of compressed zone, deflections.
The article considers the concentration dependence of dust particles PM2.5 and PM10 on a curb stone on a number of influencing parameters. According to the data of field measurements, a quadratic regression equation was compiled, according to which the factors that have the greatest influence on the spread of fine dust near the roadway were determined. The results of mathematical processing of experimental data are presented in the form of a graph of the confidence area of the observed and predicted values constructed using the STATISTICA software product.
Keywords: PM10, PM2.5, fine dust, roadway, linear city, concentration dependence
The article presents an analysis of existing methods for determining the stiffness parameters of bent reinforced concrete elements reinforced with external reinforcement based on carbon fibers. The results of comparing the results of the determination of stiffness by practical methods and laboratory tests are presented. As a result, general conclusions and recommendations were made for further research of this issue, as well as the general parameters of the carbon fiber-based reinforcement system needed to be taken into account.
Keywords: external reinforcement, carbon fiber, reinforcement, restoration
This article discusses the ways and methods of modifying bitumen with crumb rubber obtained from used recycled car tires. A method for modifying bitumen with crumb rubber in a two-stage technological process is proposed. The main modifiers are considered, the analysis of data from literature sources on the modification of bitumen with polymers to improve the physical and mechanical properties is given. Own research data on the modification of bitumen with crumb rubber are presented. The main conclusions are made, the analysis of the results obtained, and recommendations are made for the further use of bitumen modified with crumb rubber in a two-stage technological process.
Keywords: crumb rubber, bitumen, modification, polymer, improvement, quality, recycling, analysis, research
The forecast of fine dust pollution, the organization of monitoring and quality control of the air environment are relevant for cities with a developed transport infrastructure. The article checks the application of the distribution law for the concentration of fine dust PM2.5 and PM10 for highways of urban, district and local significance, the sample size was 50 values.
Keywords: linear city, distribution law, fine dust, roads, mixed gaussian distribution
The calculation for progressive collapse with variation and comparison of different scenarios was carried out for the frame of a unique high-rise building of a multifunctional complex. At the first stage, the calculation was performed in a quasi-static formulation, the maximum deflections for two destruction scenarios were determined. The requirements for the state of limited operability in conditions of progressive collapse are completed. At the second stage, the calculation was made in a dynamic formulation. A modal analysis of the frame was previously performed in order to determine the forms of vibrations that will correspond to the expected deformations of the structure in the event of the occurrence and development of the process of progressive collapse. It is established that the maximum deflection of the plate when calculated in a dynamic formulation is 27.6% greater than in a quasi-static one. The residual deflection after the attenuation of the oscillatory process is 4.6% less than in the static calculation. Therefore, the object of study is safe from the point of view of the possibility of an emergency situation, accompanied by partial destruction of load-bearing structures.
Keywords: parametric architecture, evolution of shaping, aerodynamics, finite element method, analytical surfaces
This article presents the results of the study, the impact of recreation on a person, the functions of recreation are presented and studied, classifications are proposed and, taking this into account, the types of recreational activities are derived.
Keywords: industrial buildings, interior space, architecture, recreational areas, interior gardening, architectural forms
The existing hot water supply system of a 17-storey apartment building commissioned in 2010 is considered and its scheme is described. A laboratory study of the dismantled sections of the defective pipeline was carried out. It is shown that the entire inner surface of the pipe is covered with longitudinal cracks of uneven shape, different lengths and depths. A microscopic examination of the pipe section revealed areas of insufficient adhesion of the reinforcing layer with the inner layer of the polypropylene pipe. It is established that the main reason for the appearance of pipe defects in the form of numerous cracks, the formation of bubbles and fracture with a short service life is associated with the formation of a rupture of bonds between layers and the use of low-quality polypropylene pipes.
Keywords: pipe, polypropylene, defect, crack, swelling, water supply, reinforcing layer, technology, construction, aluminum
The article shows the results of the dispersion analysis of natural dust in the steppe zone of the Volgograd region, obtained using a microscopic method. The integral functions and distribution of small particles in the selected samples after the application of the "dissection" method for particles up to 20 µm are presented.
Keywords: particle, dust, sample, dust of natural origin, dispersed composition, PM2.5, PM10, PM20
Abstract: The analysis of the implementation of the program "100 Gubernatorial investment projects" of the Rostov region in the pre-pandemic, pandemic and post-pandemic periods is carried out. The anti-crisis measures of the Government of the Russian Federation during the coronavirus pandemic are presented and their role in overcoming the consequences of the pandemic in various segments of the construction of the Rostov region is noted.
Keywords: Keywords: governor's investment projects, pandemic, anti-crisis measures, construction, capital investments, jobs
In recent decades, awareness of the environmental, social and economic crisis, both at the national and international levels, has prompted researchers to develop new, low-cost composites that are more environmentally friendly and safer for humans, using plant materials as reinforcing elements. Compared to conventional synthetic reinforcing materials, lignocellulosic fibers have many advantages. In addition to being renewable, inexpensive, widely available and harmless to health, plant fibers have relatively high specific mechanical properties combined with low density. However, there is a problem with the biostability of plant materials used in the production of composite materials, and to solve it, it was decided to pre-modify plant materials using the monoethanolamine (N-B) trihydroxyborate modifier. In order to find out the effect of the modifier on the plant material, the chemical composition of the plant material was determined before and after the modification. Determination of cellulose content was carried out by the nitrogen-alcohol method according to Kurshner and Hoffer; the amount of hemicelluloses was analyzed by treatment with 2% hydrochloric acid, followed by precipitation of furfural obtained by the bromide-bromate method; lignin content was determined by the Clason method using 72% sulfuric acid; and, finally, the content of extractive substances soluble in organic solvents was determined. It should be noted that, compared with the component composition of the raw plant material, there is a change, and this change is noticeable in the amount of lignin after the modification of the raw material and after extraction, which gives a decrease of almost 2.75 times. This is due to the formation of weak esters under the action of the modifier and, most strikingly, a strong increase in the amount of hemicellulose, which contributes to the depolymerization of cellulose macromolecules under the action of the alkaline modifier used. All this allows us to state that the modification of the crushed stems of Sosnowski's hogweed with monoethanolamine (N→B)-trihydroxyborate changes the composition of the components of the lignocarbohydrate complex of the substrate in the direction of reducing the degree of polymerization and the formation of esters.
Keywords: component composition, cellulose, hemicellulose, lignin, extractives, vegetable raw materials, ligno-carbohydrate complex