The paper presents an analysis of the methods for the chemical modification of biochar. The characteristics of acid and basic modifications, modifications with hydrogen peroxide, sulfonation, amination, impregnation with metal oxides, and magnetization are examined. It is demonstrated that the method of modification, the parameters of the technological process, and the nature of the modifying agent all exert an influence on the chemical composition, structure, porosity, pore size, and total specific surface area of the modified coal. The combination of methods, technological parameters, and modifiers allows for the production of sorbents for wastewater treatment based on biochar with specific properties for the sorption of certain groups of different pollutants.

Keywords: biochar, chemical modification, sorption properties, porosity, pore size

The article is devoted to solving the problem of high-precision installation and alignment of kinematic supports on ball rolling bodies, a detailed description of the design solution for precise fixation of ball rolling bodies on a flat monolithic concrete foundation during installation of a seismic insulating support and describes the phased construction of all elements of kinematic seismic insulating supports in the underground part of a high-rise building.A system of seismic-insulating kinematic supports installed in the underground part of a high-rise building is considered. An improved method of high-precision installation of kinematic seismic isolation supports is proposed, which allows to increase the accuracy of installing a seismic support on a system of four rolling elements. The technology of mounting seismic supports on the zero cycle of construction of a high-rise building is described. The advantages are evaluated.

Keywords: high-rise structure, vibration damping, roller seismic vibration compensation system, seismic insulation, high-precision installation of seismic insulating supports

As the space industry accelerates the trend to reduce development and production costs and simplify the use of space hardware, small spacecraft, including CubeSats, have become popular representatives of this trend. Over the last decade, the development, production and operation of small spacecraft has become in demand because of a number of advantages: simplicity of design, short design and production times, and reduced development costs. The main problem in the design of CubeSats is their miniaturisation. This paper presents the results of the development of the optical cell of collecting and processing video information for remote sensing systems of the CubeSat 3U format satellite, with the aim of obtaining the maximum possible image characteristics, taking into account the strict physical limitations of the CubeSat unit. In the course of the work, using computer-aided design systems Altium Designer and Creo Parametric, the structural diagram, electrical circuit diagram, topology, 3D model, as well as the design of the housing of the cell of collection and processing of video information were developed. PCB size: 90x90 mm, PCB thickness: 1.9 mm, number of PCB layers: 10, accuracy class: 5, cell height: 20 mm, cell weight: 110 grams.

Keywords: space hardware, Earth remote sensing, small spacecraft, nanosatellite, printed circuit board, small satellite development trend, printed circuit board topology, CubeSat

The article provides an analysis of the state of the rationing issue in terms of performing the calculation justification and design of reinforcement of reinforced concrete structures using external reinforcement systems based on carbon fibers. The normative documents of the Russian Federation and foreign ones are considered, the analysis of the use of external reinforcement based on composite materials for structures of various types of work is carried out, the disadvantages of existing calculation and design methods are highlighted. In conclusion, recommendations are given on the appropriate improvement of calculation and design methods.

Keywords: external reinforcement, carbon fiber, reinforcement, restoration

This article discusses the automation of metrological ensure at manufacturing enterprises and in metrological laboratories with a special focus on innovative technologies, including the introduction of enterprise resource planning systems (ERP systems) and the use of calibrator standards. The functioning of automated measuring systems that implement pre-established algorithms for control and testing measuring instruments is considered. An analysis of existing solutions on both the domestic and foreign markets was carried out. In particular, the focus is on a meter designed for testing integrated circuits. The possibility of integrating these measuring systems with software at various levels is discussed, as well as the prospects for their use in mass calibration of measuring instruments. The use of automated measuring systems can significantly speed up the calibration process, eliminating the need for manual voltage regulation and thereby minimizing the influence of the human factor on the accuracy of measurements. The adaptive capabilities of the software are discussed, which allows the system to be used for various types of measuring instruments, such as ammeters and ohmmeters. The findings confirm that automation of calibration processes not only significantly speeds up this operations, but also ensures strict adherence to all procedures, which helps improve the quality and reliability of the resulting measurements.

Keywords: Measuring systems, verification, calibration, measuring instruments, , automation, voltmeter, verification procedure

This work solves the problem of increasing the effectiveness of educational activities by predicting student performance based on external and internal factors. To solve this problem, a model for predicting student performance was built using the Python programming language. The initial data for building the decision tree model was taken from the UCI Machine Learning Repository platform and pre-processed using the Deductor Studio Academic analytical platform. The results of the model are presented and a study was conducted to evaluate the effectiveness of predicting student performance.

Keywords: forecasting, decision tree, student performance, influence of factors, effectiveness assessment

The paper deals with the construction of an algorithm for nonparametric estimation of the transition probability distribution density for the Markov model of the dynamics of the number of university employees. The problem of reconstruction of transition probability distribution density on a retrospective sample of small volume is solved. The result of the solution is the transition probability matrix, the elements of which are random variables with distribution laws obtained from retrospective data. A distinctive feature of the algorithm is the simultaneous consideration of regional and functional constraints on the values of transition probabilities. The convergence of the algorithm has been experimentally confirmed.

Keywords: probability density, nonparametric estimation, Markov model, simulation modeling, university staff movement, publication activity

The article presents the results of a survey of two industrial buildings, conclusions about their emergency technical condition and the inexpediency of restoration. Modern methods of demolition and dismantling of buildings in the cramped conditions of the existing urban development are analyzed. The main technologies of recycling dismantling and disposal of construction waste generated during the dismantling of buildings are considered: "smart demolition" and the technology of piecemeal disassembly of buildings with the reuse of materials, products and structures. Comparing the two methods of recycling dismantling for application to the objects under consideration, it is concluded that the first method of "smart demolition" implies the destruction of all building structures, while the second is more rational in terms of resource conservation and economic efficiency by reuse of serviceable structures. The technology of piecemeal disassembly of buildings with the reuse of structures requires the development of regulatory, organizational and marketing measures.

Keywords: building inspection, demolition, dismantling, dismantling methods, smart demolition, recycling dismantling, reuse of structures

The issues of preserving existing green spaces and other elements of the natural landscape during new construction are considered. Methods for preserving perennial plantings throughout the entire course of construction are proposed. If it is impossible to save the tree at the construction site, a method of transplanting it to another place is proposed. It is proposed at the stage of design and survey work to identify healthy trees that do not grow on the site allocated for a building (structure) under construction. Then solve the problem of locating the object on the ground in such a way as to preserve healthy perennial trees as much as possible. To do this, it is necessary to carry out the removal of the object to the area, moving it as far as possible from healthy trees. The distance required to protect the tree from external influences during work is equal to the projection of the crown on the ground plus 1.5 m. At this distance, it is recommended to make stationary fences for each tree. A tree transplantation scheme and a method for calculating its weight for the selection of equipment for digging and transportation have been developed.

Keywords: landscaping, construction, tree, tree transplanting, asphalting

This article discusses the solution of the problem of monitoring contact information in a social network and determining the personality psychotype based on it. Most of the material proposed by the developers works with English-language texts to determine the emotional coloring, their classification and, to a lesser extent, clustering. The approach proposed in the article is based on the use of the K-means method to solve the clustering problem of Russian-language texts and subsequent comparison with the results of working with the same data of an already trained model. During the work, was developed an effective method of parsing for collecting data. A proprietary data set has been collected and its processing and detailed analysis have been carried out. The result of the study allows us to make a primary assumption about what kind of psychotype a particular person has. It is quite difficult to determine the accuracy of the results of the task, since there is no predefined correct answer in machine learning without a teacher, and determining the psychotype is a difficult task from the point of view of psychology. All program code is written in the Python programming language.

Keywords: clustering, psychotype, social network, sanguine, phlegmatic, choleric, melancholic

The assumptions of mathematical models for calculating the crack resistance of reinforced concrete structures are considered. For each of them, an analysis was carried out to determine whether they correspond to reality throughout the entire life cycle of the structure: from the hardening of the concrete mix to destruction. Based on the results of the analysis, it was proposed to use only one single calculation at the level of standards to assess the crack resistance of structures - according to the crack opening width, acrc. So, for example, at a certain value of acrc, the structure will still remain airtight (the cracks will be non-through), and if this value is exceeded, it will not. At the same time, the calculations already available in the norms for limiting permeability and the safety of reinforcement will still remain in demand. At the junction of the theory of damage accumulation and nonlinear fracture mechanics, a compressed algorithm is proposed for possibly taking into account the influence of cracks at all scale levels of the concrete structure, the key for which is the normalization of the statistical parameters of the distribution of discontinuities by diameters, lengths, openings, depths, directions, distances between discontinuities, etc.

Keywords: reinforced concrete, crack resistance, cracking moment, crack width, plasticity coefficient, damageability, non-linear fracture mechanics

The article discusses a mathematical model of an excavator's hydraulic shears, which describes the functional dependencies of their main parameters based on regression statistics. An algorithm for the process of selecting optimal parameters for hydraulic shears used to destroy metal structures during the dismantling process is presented, and a description of the developed software application that automates the process of selecting these parameters is given. The application described in the article will reduce the time required for the design stage of excavator attachments.

Keywords: attachments, hydraulic shears, dismantling, metal cutting, design, mathematical model, automation, selection of parameters, algorithm, program

At the beginning of 1908, the Tsarskoye Selo Community of the Sisters of Mercy of the Red Cross was organized in the city, which was allocated a plot for the construction of a building for an outpatient clinic and a dormitory of the sisters of mercy with a church. The development of the project and supervision of the construction was carried out by architect S.A. Danini. Construction of the building was started in 1912 and completed in October 1914. The internal load-bearing structures of the building were made of monolithic reinforced concrete, central water heating and ventilation system were used. Building survey in 2017-2019 it has shown that it is possible to reconstruct it for a day-stay boarding house for disabled children.

Keywords: Tsarskoye Selo, S.A. Danini, Community of the Sisters of Mercy of the Red Cross, architectural planning solutions, reinforced concrete structures, building surveys, church in honor of the Icon of the Mother of God of All Sorrowing Joy

The article is devoted to the development of a computer program with the help of which it is possible to simulate the number of flowing and non-flowing cultures of microorganisms for educational purposes. The Mono model is taken as the basic model of biomass growth. The apparatus of ordinary differential equations is used for the mathematical description of cell populations. As a result, the structure and functionality of the electronic learning module with its subsequent implementation in Python has been developed. As a result, the laboratory work "Modeling of flowing and non-flowing cultures of microorganisms" was developed, in the form of a computer program, performed within the framework of mastering the discipline "Biophysics" and consisting in studying the basic principles and methods of modeling the processes of development of microorganisms in flowing and non-flowing cultures. The developed program is implemented in the educational process.

Keywords: computer program, cell population, biophysics, microorganisms, computer modeling, Mono model, Python, biomass, flow conditions, non-flow conditions, system of equations

In the modern world, the number of different complex technical systems is only increasing every year, and any system incorporates or uses a third-party communication system. Disruption of the communication system and its elements functioning can lead to a situation where a complex technical system cannot realize its functions. It is required to ensure the guaranteed functioning of the communication system and its elements. One of the ways to ensure the stable operation of complex technical systems is the implementation of the control function by the control system, while in the process of system operation it is necessary to take into account not the characteristics and parameters of individual elements that describe their operation, but the ability of the system to perform tasks and functions. The paper proposes an approach to describing the functioning of a communication system through the formation of the system functioning profile, which is a set of matrices, which is used in the control system.

Keywords: functional stability, criticality, communication system, control system, complex technical system, functions, tasks, profile, regulations