Using numerical simulation, particle deposition in a porous heat exchanger was studied; the mechanism of sediment formation was sinvestigated, and the influence of sediment on the heat flow was assessed. The influence of porous heat exchanger length, dust particle size, and air flow velocity on particle deposition efficiency, particle breakthrough, and heat flux value was studied. Research results have shown that with increasing length of the heat exchanger, the efficiency of dust particle deposition increases, which leads to the formation of sediment. In turn, the sediment reduces the value of the heat flow from the porous heat exchanger. Depending on the length of the heat exchanger and air velocity, the reduction in heat flow is 3.43-7.27%.

Keywords: porous media, heat exchanger, particle deposition, deposition efficiency, particle breakthrough, sediment, heat flow, numerical modeling, computational fluid dynamics, calculation

The article discusses methods for optimizing floating point calculations on microcontroller devices. Hardware and software methods for accelerating calculations are considered. Algorithms of Karatsuba and Schönhage-Strassen for the multiplication operation are given. A method for replacing floating-point calculations with integer calculations is proposed. Describes how to use fixed point instead of floating point. The option of using hash memory and code optimization is considered. The results of measuring calculations on the AVR microcontroller are presented.

Keywords: floating point calculations, fixed point calculations, microcontroller, AVR, ARM

Using numerical modeling, we performed studies of the influence of the angle of inclination of the plates of the regenerative heat exchanger element on the heating time and pressure drop. The studies were conducted for models of heat exchange elements with lengths of 6 and 20 mm. Depending on the length of the element, the angle of inclination of the plates was: 10°, 20°, 30°, 40° (at L=6 mm) and 3°, 6°, 9°, 12° (at L=20 mm). At the boundary of the calculation area, the air flow velocity and temperature were established, namely 1 and 3 m/s, and 303 and 973 K. The research results demonstrated that increasing the angle of inclination of the plates helped reduce the heating time of the regenerator by 38.56-49.1%, depending on the length of the heat exchange element, the speed and temperature of the air flow.

Keywords: heat recovery, honeycomb heat exchanger, numerical modeling, calculation, heating time, pressure drop, heat exchanger geometry, angle of plate, air flow velocity, air flow temperature

Using numerical simulation, we carried out studies on the effect of the length of a porous heat exchanger on the deposition of dust particles. The heat exchanger models with lengths of 5, 10, 20 and 30 mm were the subject of the studies. At the boundaries of the computational domain, we set the air velocity at 0.1, 1, and 5 m/s and the diameter of dust particles from 10-7 to 10-4 m. Research results have shown that with increasing length of the porous heat exchanger, the efficiency of dust particle deposition increases. This can lead to a decrease in the thermal and hydraulic characteristics of the heat exchanger.

Keywords: porous media, heat exchanger, numerical simulation, calculation, deposition of dust particles, heat exchanger length, air flow velocity, particle diameter, air cooling, microelectronics

The article discusses a graphical notation using three-dimensional visualization for representing models of automated systems according to the Methodology of Automation of Intellectual Labor (MAIL). The research aims to enhance the efficiency of modeling automated systems by providing a more comprehensive representation of the models. Research methods employed include a systems approach. The study results in the formulation of descriptions and rules for creating the corresponding graphical notation for the initial and conceptual modeling stages of subject tasks in MAIL, as well as rules for forming representations for static and dynamic model structures and representing their interrelations. Additionally, rules for visually highlighting and concealing elements within the diagrams of the graphical notation are examined, rendering it suitable for implementation as a software module with a graphical interface for CASE tools, facilitating modeling according to MAIL. Such an approach enables the visualization of the model as a whole and enhances the efficiency of analysts conducting modeling following the methodology.

Keywords: methodology of Automation of Intellectual Labor, modeling of automated systems, conceptual modeling, graphical notation, three-dimensional visualization

This article reveals a number of examples of the features of the construction of the base of a gravity offshore platform used for the extraction of hydrocarbons. The design of the reinforced concrete base of the platform in the form of a "monopod" consisting of 8 lower cylindrical tanks and a vertical reinforced concrete support with a length of 95 m is considered. Reinforcement of the entire structure was carried out by pre-tensioning reinforcement ropes on the hardened concrete in height by mechanical means. During the construction of the gravity foundation, new compositions of heavy high-strength modified concretes with the use of microsilicon and nanocarbon additives were used. During the construction process, adjustable formwork was used along the entire height of the structure.

Keywords: gravity platform base, monopod, pre-tension on concrete, high-strength modified concrete, towing, positioning

The effectiveness of fly ash from the Novo-Irkutsk Thermal Power Plant and ash and slag mixtures from Thermal Power Plant-10, formed during the combustion of solid fuel fossils of JSC Irkutskenergo, in the composition of cements with low water demand has been shown. The chemical composition and physical and technical properties of this waste have been determined. The grindability was studied and the specific energy consumption of cements with different ash contents (30-70%) was calculated. It has been established that low-water-demand cements with fly ash and ASM are not inferior to Portland cement in technological and physical-mechanical indicators, and can be recommended for use in construction.

Keywords: large-tonnage waste, ash and slag mixtures, grindability, low water demand cement, superplasticizer, joint grinding

A program for computer simulation of atomization of liquid fuels has been developed. A special calibrating experiment was carried out in a gravitational field. Verification of the computer model with experimental data is carried out, the correctness of simulation modeling is determined by the convergence of the results of static generalization. Tests of a model sample of the burner device were carried out, confirming the adequacy of computer simulation.

Keywords: burner, atomization of liquid fuels, mathematical modeling, fuel jet dispersion dynamics, nozzle

The principles and results of the formation of classification tables "Auxiliary resources" and "Human resources" of the classifier of construction information are considered. The existing world experience of data classification for the development and maintenance of information models (IM) of capital construction objects (CCS) and ways of organizing data associated with the IM: OmniClass (USA), Uniclass 2015 (UK) and Cuneco Classification System (CCS, Denmark). The developed classification tables can be used in the development and maintenance of ССS IM for the identification of auxiliary and human resources, development of process maps and calendar-network planning, for the development of design documentation in terms of construction organization and estimated cost, for cost analysis of investment and construction processes and determination of labor costs.

Keywords: construction information classifier, information modeling, information model of capital construction object, classification system, auxiliary resources, human resources

In this article, a computer simulation of the movement of passengers on escalators was carried out, taking into account different (four) scenarios for organizing the movement of passengers, the intensity of passenger flow, and also analyzes the influence of social distance on the speed of ascent. The dependences of the change in the time spent by passengers on covering the path from the center of the platform to the moment of ascending the corresponding escalator were constructed. The results of the study make it possible to identify differences in the efficiency and comfort of passenger movement depending on the chosen layout and load. These findings can be useful for optimizing the operation of public transport and metro systems, providing safer and more comfortable travel for passengers in various conditions.

Keywords: analysis of human flows, ensuring safety in the metro, organizing human flows, computer modeling, optimization of passenger flow

The article discusses the application of machine vision methods for embedded systems using modern microcontrollers. Machine learning methods that are used in embedded systems to solve recognition problems, as well as neural network models, are described. The use of trained models for solving image recognition problems in embedded systems is proposed. The architectures of YOLOv3 and R-CN neural networks are compared. The Jetson TX2 hardware platform is considered. The results of comparing the calculation speed for different modes of the device are presented.

Keywords: machine vision, neural networks, artificial intelligence, embedded systems, pattern recognition, YOLO, RCN, Jetson, Tensorflow

The features of classification of construction products and construction materials are considered, and optimization of their existing classification structure is proposed. The analysis of existing domestic and international systems of classification of construction information, domestic normative and technical literature is carried out and classification features for construction material and construction product are determined. The optimization of the classification tables (CTs) based on the application of the principles of the ISO 81346 standard series and the refusal to duplicate the structure of the construction resources classifier, on reducing the number of classes and subclasses taking into account the ISO 81346 criteria and moving classes and subclasses within CTs with the corresponding changes in the code designations is suggested.

Keywords: construction information classifier, information modeling, information model of capital construction object, classification of construction materials and products

The current trend of complication of the modes of operation of the traction power supply system, an increase in the amount of damage from events leading to downtime of trains, the need to improve operational efficiency, actualizes the task of using monitoring systems. The features of the traction power supply system determine the requirements for the organization of monitoring parameters in real time. One of the main requirements is to ensure the autonomous operation of monitoring devices (systems) for a given period of time. Using the example of monitoring the process of ice formation on a contact network, taking into account the specifics of disturbing environmental influences, the basic principles of building a monitoring system, the structure of technical means, a multi-mode algorithm of functioning, a method for calculating the parameters of a power source are proposed.

Keywords: power supply system, contact network, monitoring, ice detection, automation

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

When solving the problem of ensuring the mechanical safety of buildings and structures according to GOST 27551-2014 “Reliability of building structures and foundations. Basic provisions” it is allowed to apply a risk-oriented approach. A mandatory stage of this approach is the forecast of the expected accident risk situation of the facility. Due to the fact that the current regulatory documents on risks do not reflect all the features of the stress-strain state of building structures and foundations of buildings and structures during the operation of structures and, therefore, do not allow for a sufficiently accurate assessment of the safety of structural systems, risk assessment for building structures is a very relevant scientific and technical problem.

Keywords: building, building structures, design, destruction, safety, accident risk, risk assessment, risk management, monitoring and risk analysis