This paper is devoted to optimization of surface acoustic wave bandpass filters with apodized interdigital transducers (IDT). Iterative Parks-McClellan algorithm is applied to estimate the apodization coefficients of the IDT fingers. A family of corresponding subroutines is developed in the Matlab mathematical package. The simulation results of the SAW filter optimized design are illustrated. For the refined estimation of the filter frequency response COM-based P-Matrices are employed. The results obtained in this study constitute a set of tools for the practical calculation of apodized IDTs and filters according to a given specification. Subroutines implementing COM-based P-Matrices can be utilized as part of programs for frequency-selective SAW devices design.

Keywords: acoustoelectronics, apodization, approximation, interdigitated transducer, impulse response, surface acoustic wave, optimization, piezoelectricity, filter, frequency response

The article considers the problem of sediment formation, sludge and corrosion on the heat transfer surface during the operation of heat exchange equipment at housing and communal services facilities. A new method of non-selective mechanical cleaning using a water hammer is proposed. The description and principle of operation of this cleaning system at the central heating station of the Ogarev Moscow State University are given. To confirm the effectiveness of the proposed technical solution, the results of thermal and hydraulic tests are presented.

Keywords: deposits, sludge, corrosion, cleaning, heat exchanger, water hammer, heat transfer

The article discusses the use of a recurrent neural network in the problem of forecasting pollutants in the air based on actual data in the form of a time series. A description of the network architecture, the training method used, and the method for generating training and testing data is provided. During training, a data set consisting of 126 measurements of various components was used. As a result, the quality of the conclusions of the resulting model was assessed and the averaged coefficients of the MSE metric were calculated.

Keywords: air pollution, forecasting, neural networks, machine learning, recurrent network, time series analysis

The construction industry is undergoing regular changes these days, influenced by many different factors. Large and structurally complex construction projects reveal more and more imperfections in traditional construction methods, e.g. increased time or production costs, downtime, delays, etc. Lean construction and its principles have emerged in search of solutions to problems in construction. In the search for solutions to problems in construction, the term - lean construction and its principles appeared, which replaced traditional methods and aimed at finding new approaches in the implementation of construction activities. In this scientific article the definition of Lean Construction is given, and also the history of Lean Construction and its chronology are considered. The comparison of the traditional construction model and Lean model is given, and also the connection of Building Information Modeling (BIM) with Lean Construction principles is analysed and an example of this connection is given.

Keywords: lean manufacturing, lean construction, construction, lean construction principles, lean technology, lean model, lean philosophy, life cycle of an object, information modelling technologies, engineering

The article presents a way to increase the load-bearing capacity of a reinforced concrete column due to metal clips from the corners with an increase in the load on it. To ensure the joint operation of the existing column and the metal cage, the corners are subjected to prestressing, which is achieved by compressing the corners with jacks.

Keywords: reinforced concrete column, column reinforcement, metal cage, prestressing of the cage

The practical significance associated with the development of automated software systems for calculating joints of steel structures of buildings and structures is noted. Using the IDEA Statica software package as an example, the calculation and analysis of the operation of a steel unit connecting the lower chord of a truss to a column was carried out. The order and sequence of entering the initial data for calculating the connection is shown. The calculation results present in tabular and graphical forms the equivalent stresses and plastic deformations of the main elements, as well as the results of inspections of bolted and welded connections of these elements to each other. A comparative analysis of numerical and analytical calculations was performed. Conclusions are formulated based on the results presented in the article.

Keywords: calculation model, connections, steel structures, component finite element method, design, nonlinear analysis, work analysis, stress, plastic deformation, bolted connection, welded connection

The main means of seismic protection for increasing the seismic resistance of buildings and structures are described. The main problems associated with the design of special seismic protection equipment are outlined. The basic requirements for the design and calculations of steel frame frames taking into account seismic impact in accordance with the current design standards in the Russian Federation are analyzed. There is an insufficient description of the requirements specified in the standards for performing calculations and design of structures and their connections. Recommendations and instructions are given for taking into account the requirements of the standards for the design of steel frame frames. Schematic diagrams of special units for coupling columns with crossbars, necessary for design in seismically hazardous areas, are presented. Conclusions are formulated.

Keywords: special units, columns, beams, seismic impact, seismic protection, steel frames, plastic hinges, excess strength factor, forces, plastic moment, design.

The effect of organomodified silica particles on the extraction of dissolved diesel fuel from water was studied. The dependence of the efficiency of water purification on the concentration and type of solid particles, as well as the concentration and type of surfactant, is shown. When using a short-chain surfactant to modify the surface of silica particles, the minimum residual concentration of diesel fuel was 2.71 mg/l at a concentration of 4% Aerosil-380 and hexylamine 57 mmol/l. Replacing the short-chain surfactant hexylamine with the long-chain CTAMB led to an 8% improvement in the quality of water purification due to an increase in the surface activity of the organic cation. The use of modified clay particles to purify water from diesel fuel showed lower efficiency compared to Aerosil-380 particles at similar concentrations of the solid phase and surfactant modifier.

Keywords: Pickering foam, foam emulsion, diesel fuel, water purification, silica, cationic surfactant, hexylamine, cetyltrimethylammonium bromide

The paper presents a solution to the problem of accelerating the process of visualizing the results of numerical simulation. The volumes of such data can be very large and the development of tools to speed up the process of analyzing modeling results is an urgent task. This article proposes a solution to the problem based on the development of a set of programs that automate the process of processing large-volume scientific data of the same type to create high-quality visualizations of the results of numerical modeling. The results are presented using the example of solving problems in astrophysics, but the proposed methodology can be quite easily applied to other subject areas in which models based on the dynamics of particle systems are used. The research described in the work is devoted to solving issues related to converting data obtained from numerical modeling into a format that can be read by the ParaView softwart, which implements many methods that allow obtaining very high-quality visualization. The work also describes the process of automating batch processing of a large amount of data that has the same structure, presents the results of an analysis of the acceleration of the visualization process when using the NVIDIA IndeX plug-in, and considers the possibility of improving the quality of visualization results when applying Delaunay triangulation to the original data.

Keywords: data visualization, Delaunay triangulation, rendering acceleration, ParaView, NVIDIA IndeX, VTK

The article discusses proposals for improving the use of discharge-pulse technology in the construction of boron-injection piles and camouflage widenings of bored piles with diameters of more than 300 mm. The application of voltages on the electrode system of a pulse current generator from 10 to 50 kV and an electric capacity of about 300 UF is considered. It has been found that in the case of using a relatively low voltage on the electrodes and an increase in the electrical capacity of the capacitor bank, the duration of the shock wave pressure on the ground increases several times. This contributes to a more intensive penetration of the liquid hardening material into the intergranular space of the near-well soil massif. It is proposed to use solutions using slag-alkali binders as a hardening material in the formation of boron-injection piles. Such solutions have greater fluidity compared to cement solutions and, when hardened, form a stone with greater strength and density. The article presents data from experimental studies confirming the increased strength (R = 130 MPa) and frost resistance of a solution prepared on slag-alkali binders, as well as data on determining their corrosion resistance to various aggressive media contained in groundwater. The possibility of stable breakdown of the interelectrode gap in aqueous solutions of slag-alkali media of various consistencies has been established, optimal energy parameters of the discharge have been determined for maximum effect of fixing the soils of the foundations.

Keywords: foundations, drilling piles, discharge-pulse technology, slag-alkali binders

This article discusses the results of studies of the behavior of reinforced concrete slabs during punching. The parameters affecting the shear strength of the joints of columns and slabs are considered. Studies of the influence of the strength of concrete, the location of reinforcement, the reinforcement coefficient, the shape and size of the column are given. Various types of reinforcement of reinforced concrete slabs in the punching zone are presented.

Keywords: floor slab, column, punching, shear, bending, transverse reinforcement, dowel action

This article examines models of arithmetic devices for finite ring neural networks of the second and third orders. The arithmetic devices under study were synthesized on the basis of FPGA. Estimates of hardware costs and performance of computers for system modules of residual classes of different capacity were obtained. The structure of a finite ring neural network with dynamic connections is proposed, the efficiency of which in terms of hardware costs is observed with increasing capacity of the residue number system module. The advantage of a finite ring neural network with dynamic connections is established for modules with a capacity of 64 bits and higher.

Keywords: neural networks, residue number system, group of elliptic curve points, FPGA, multiplier, adder

The paper describes the process of modeling 3D structures of synthetic gas burners, with the analysis of the simulation results obtained for several types of models and the selection of optimal modes for them. The main use of the burner is planned for boiler equipment for household needs in private as well as apartment buildings, in the absence of central heating. In addition, the article provides a justification for the thermal parameters at the inlet and outlet of the burner.

Keywords: synthesis gas, combustion, design parameters, combustion chamber, nozzle, modeling

The production of nitrogen from air using membrane gas separation processes is widely used in many industries. The problem of controlling the gas separation process is associated with multi-loop control using control of several variables. To build a model of a gas separator, a detailed analysis of the gas separation process was carried out in this work. This article proposes a fuzzy logic controller used to match pressure fluctuations and air flow of a gas separator. The performance of the proposed controller was evaluated in comparison with traditional controllers. The proposed fuzzy logic controller makes it possible to increase the accuracy of the gas separation control system and reduce the duration of transient processes.

Keywords: fuzzy logic, controller, gas separation, membrane technology, nitrogen, control system

The article is devoted to applied issues of improving regional security management processes through the development of methods for analyzing data on emergency situations. In order to identify patterns in the occurrence of emergency situations, multidimensional methods of processing statistical data were used. A multidimensional classification of data in the field of emergency situations based on fuzzy logic is proposed. The classification was performed using a fuzzy inference system with clear membership functions. As statistical data, data on emergency situations of a man-made, natural and biological-social nature that occurred in the federal districts of Russia in 2020, including data on dead and saved people, were considered. An analysis of data samples on regional emergency situations was carried out according to 5 criteria, and clustering of regions was carried out.

Keywords: emergency situations, fuzzy multidimensional clustering, fuzzy logic, fuzzy inference system, computer program, mathematical model, forecasting, decision making