The article analyzes the testing time of the control system on the test bench, identifies the components of the testing time, and provides the calculation procedure for a typical test bench. The results obtained can be used to estimate the time of testing control systems at the design stage of test benches.

Keywords: automatic control system, rocket and space technology, test bench, analysis of the testing process, experimental testing, testing time

The features of the functioning of steel structures in an aggressive environment are considered, the results of a qualitative and quantitative assessment of the nature of damage to a profiled sheet are given.

Keywords: steel structures, building structures, corrosion, aggressive environment, zinc coating, corrosion rate

The article deals with the problem of disposal of the sludge formed after the treatment of wastewater at the production of chemical fibers. Sludge after sedimentation is stored in storages and pollutes the environment. We carried out a comparative analysis of existing methods of disposal of sewage sludge from chemical production, which showed that the most environmentally friendly way is pyrolysis. We have analyzed the chemical and fractional composition of ash sludge after pyrolysis. The analysis revealed that the resulting ash waste is similar to ash from coal-fired power plants, which makes it possible to use it as a microfill for paving roads or sidewalks. By selling the ash waste it is possible to reduce the payback period of the pyrolysis unit installation and reduce the ecological load on the environment.

Keywords: pyrolysis, sludge, sediment, ash, disposal

The article assesses the impact of road transport on air pollution of roadside areas of a major transport highway in Volgograd. The road-car complex makes a significant contribution to air pollution by solid particles, significantly exceeding the background value. One of the criteria for assessing the impact of dust particles on the air environment according to the World Health Organization is the mass content of particles with a diameter of less than 10 microns (PM10) and 2.5 microns (PM2.5) in atmospheric air, which is normalized in the territory of the Russian Federation by hygienic standards. The fractional composition of dust particles entering the atmospheric air was assessed by the Microtrac S3500 laser particle analyzer, the concentration by the Lighthouse 3016-IAQ particle counter. The results of the dispersion analysis are presented in the form of the Rosin–Rammler–Sperling–Bennett function of the volume distribution of particles over diameters.

Keywords: dust, particle, dispersed composition, concentration, road transport, atmospheric air, transport highway

In this study, the thermal properties of porous materials with the topology of triply periodic minimal surfaces (TPMS) of Schwarz are investigated. By generalizing the results of computational experiments, the dependencies of the thermophysical properties of TPMS materials on macrostructural parameters such as size and thickness of the elementary cell have been obtained. The properties of the most common thermoplastic polymers PETG, ABS, PLA, and PHP used in additive manufacturing have been explored. It is demonstrated that the thermal conductivity coefficients of the examined TPMS materials can be represented as a linear function of the dimensionless geometric parameter – the relative thickness of the elementary cell wall. By varying this parameter, and consequently the geometric structure of the porous medium, it is possible to obtain a material with desired thermophysical properties. Verification of the obtained finite element method results is conducted based on the analysis of mesh convergence of solutions.

Keywords: effective thermal conductivity; heat transfer; porous material; porosity; thermoplastic polymer; ordered macrostructure; Schwarz minimal surface; triply periodic surface

The possibilities of a little-studied method for obtaining nanosized materials of electronic engineering with a given substructure, the zone sublimation epitaxy (ZSE) method, are discussed. In the work, it is combined with the method of gradient liquid phase epitaxy (GLE). A specific feature is mass transfer in a two-phase medium (a solid substrate and an inert gas phase acting as a transport medium) with preliminary deposition of a matrix layer formed from the melt. A feature of the sublimation process in the study was the crystallization of low-melting iron-silicon eutectic. A mathematical model of the process was proposed and compared with the experimental results. Island structures of the composition silicon (more than 90%), iron (up to 8%) and chromium (about 1.5%) have been obtained. Their parameters and size distribution were studied. A Solver-HV scanning probe microscope and a Quanta-200 scanning electron microscope were used. The study shows that the use of sublimation transfer transients makes it possible to reproducibly form doped silicon nanolayers and transform them into regular mesostructures.

Keywords: microsize growth cell method, zone sublimation epitaxy, gradient liquid phase epitaxy, island nanostructures

In the field of design and construction of transport facilities, in particular railway transport, Industry 4.0 technologies are gradually being used. In the transport industry, the concept of "digital twins" - a computer representation of a real object - has become especially widespread. The basis for "digital twins" are information models (TIM-models). At the present stage of the development of these technologies, the method of applying TIM for linear-broaching objects has not been worked out to the end. This paper considers the experience of designing railway infrastructure facilities using information modeling technologies in Russia and in the world. The concept of the methodology for the practical implementation of information modeling technology for railway infrastructure facilities at the design stage is proposed. The main limitations of the presented methodology and ways to overcome them are considered.

Keywords: BIM, information model, railways, railway information modeling technologies, information modeling methodology

One of the methods for strengthening connections in steel trusses made of cold-formed welded profiles is the use of plate overlays. This article presents their influence on increasing the strength of connections according to the criterion of bearing capacity under compression. The investigations were conducted using the component finite element method. The obtained dependencies of the increase in bearing capacity are demonstrated based on the width and angle of the brace connection. An engineering methodology has been developed to assess the strength of the reinforced connection under compression, utilizing a traditional formula from Russian design standards with the substitution of the thickness of the chord by the equivalent thickness.

Keywords: : reinforcement, connections, cold-formed profiles, bearing capacity, compression

The article analyzes the shaping of buildings and structures in modern architectural practice. Form in architecture is primarily a means of expressing and translating concepts. It's also what ultimately fills and divides the space we live in. Form in architecture can have great symbolic and cultural significance and can transform a space for the better or for the worse. The simplest of the forms are known as primary forms. The main shapes include circles, triangles and squares. Each form can be created by a combination of basic forms. When rotated or expanded, basic shapes can create three-dimensional volumes known as basic bodies. In modern architectural practice, it is very common to resort to the use of complex shapes created using spatial curves. The task of the architect is a complete visual representation of such forms in drawings, as well as using modern software graphics packages. The article raises the problem of the correct interpretation of architectural forms formed by such spatial curves (using the Hilbert curve as an example).

Keywords: architecture, spatial curves, axonometric projections, Hilbert curve, modernism, shaping, ornamentation, space

The article presents and substantiates the structure of the original combined pathospecific measuring device for the diagnosis of glaucoma, which will allow for a comprehensive analysis of the hydro- and hemodynamics of the eye and thereby improve the quality of glaucoma diagnosis. Based on this structure, a detailed metrological analysis of this installation as a means of biomedical measurements was given in the work. Brief conclusions on the work are given and prospects for the further development of the project are determined.

Keywords: combined pathospecific measuring device, tonometry, rheography, sphygmography

Prompt adjustment of the composition of the asphalt concrete mixture is key to achieving high quality asphalt concrete. To enable easy and rapid adjustment of the asphalt concrete mixture formulation, predicting the properties of asphalt concrete (Marshall stability) is critically important. There are many methods for predicting the properties of asphalt concrete, but the choice of one method or another is a very pressing problem. This article proposes two methods for forecasting Marshall stability: forecasting using a multiple linear regression model and forecasting using an autoregressive model. To evaluate the forecasting accuracy of models, we use two metrics: average absolute error (MAE) and average absolute percentage error (MAPE). The results of the study show that the autoregressive model exhibits better forecasting results, especially the second-order autoregressive model.

Keywords: asphalt concrete, control, composition adjustment, forecasting, multiple linear regression model, autoregression model, Marshall stability, forecast accuracy, mean absolute error, mean absolute percentage error

The article considered retail as a system that includes complex systems. involves consideration of a proposed system associated with multiple non-linear relationships and the presence of hidden influences. Proposed an application of the algorithm for solving a reverse problem during strategic planning in retail to help in understanding complex processes that change depending on the effectiveness of the implementation of the strategy.

Keywords: strategic planning, retail, reverse modeling perspective, fuzzy cognitive maps, management in complex systems

When erythrocytes move along a narrow capillary, they take an asymmetric shape and roll along the capillary like a tractor caterpillar (tank - treading motion). The shape of the erythrocyte is approximated by a truncated cylinder and is uniquely determined by the diameter of the erythrocyte in the capillary, the volume and surface area of the erythrocyte. Other input parameters are the speed of the erythrocyte in the capillary, the frequency of rotation of the erythrocyte membrane, the charge of the erythrocyte, and the number of closed trajectories along which the charges move. It is assumed that the negative charges located on the membrane are equal in magnitude and distributed evenly over the membrane and move along closed trajectories together with the membrane. From the last parameters, you can find the number of charges on the erythrocyte membrane. According to the Biot-Savart-Laplace law, mobile charges generate a magnetic field in the surrounding space. Using computer calculations, the distributions of the magnetic field strength were obtained both near a single erythrocyte rolling along a narrow capillary, and near a capillary along which several erythrocytes move, at various values of hematocrit. The dependence of the maximum value of the magnetic field strength near the capillary on the hematocrit is found. In particular, it was shown that at a distance from the capillary equal to 8 capillary diameters, the maximum value of the magnetic field strength increases by a factor of 1.29–1.36 (depending on direction) with increasing hematocrit from 12.27% to 18.25%.

Keywords: mathematical model, magnetic field, charge, membrane, erythrocyte, capillary, hematocrit

The article is devoted to mathematical modeling of construction of underwater tunnels intended for subway. This type of tunnels can also be used as railway and road tunnels. The most interesting are underwater tunnels-bridges and floating tunnels, but the most perspective and most frequent are tunnels located at the bottom of water barrier.

Keywords: underwater tunnel, subway, finite element method, leave section method, mathematical modeling, construction technology stages, transport tunnel, stress-strain state

Yemeni cities are urbanizing so rapidly that there will soon be no room for green spaces. In this regard, there is a need to find solutions to provide citizens with the "green" infrastructure necessary for life and health. This article presents the results of an urban planning analysis of the study of existing territorial reserves suitable for the formation of the "green" frame of the city of Ibb, their capacity and structure. Based on the analytical data obtained, the concept of the "green" frame of the city of Ibb was proposed, on the basis of which the system of architectural and urban planning principles for organizing the "green" recreational frame of the Yemeni highland cities was expanded and supplemented.

Keywords: urban planning, urban greening, sustainable development of the city, landscape design, urban environment, reconstruction