A more adequate methodology for assessing the overall risk of untimely completion (construction and installation works - CIW), taking into account the time horizon of risk occurrence and the phenomenon of risk competition from both probability and impact perspectives, is justified. One of the most common problems in construction projects is delays caused by risks. However, existing research on risk assessment and project schedule analysis overlooks the fact that the aggregate risk depends on the sequence of risk occurrences and their interactions. This article presents a decision algorithm and justifies a computational method for determining the risky duration of work in the project schedule. This information is crucial for making adjustments to the schedule and developing effective risk response strategies. In the calculation examples we have provided, we have demonstrated that our approach differs from the classical method.

Keywords: "probabilistic planning, delays, aggregate risk, risk assessment, uncertainty, construction management, quantitative analysis, timelines, investment projects"

The paper calculates the probability of failure-free operation of parts of the supporting structure of foreign-made lifting equipment designed to perform loading and unloading operations of stone building material. When performing calculations, computer modeling of the stress-strain state by the finite element method was used. A distinctive feature of the proposed calculation methodology is the minimum required number of computer experiments, given that some of the input data are variable.

Keywords: probability of failure-free operation, lifting equipment, reliability

A method for recording holograms using digital cameras with high spatial resolution is considered. To register holograms obtained in optical setups with an inclined reference beam, a high resolution of registration systems is required. To do this, it is necessary to use media with a resolution of 2000-4000 lines per mm. The use of photographic plates requires a fairly long exposure and development time, which is usually done separately from the optical setup. In the case of holographic interferometry systems, it is necessary to provide for mounting the hologram back into the optical setup with sufficiently high accuracy. Therefore, digital holography methods have been developed to record holograms on photomatrices with limited resolution. These methods are based on the use of optical schemes at small angles (less than 5 degrees) between interfering beams. Recently, sensors with a single element size of 1.33 µm and 0.56 µm have appeared. This resolution makes it possible to return to registration schemes with angles between interfering beams of 30-60 degrees. This allows us to hope for the revival of holographic methods and methods of holographic interferometry at the modern level without the use of intermediate recording media.

Keywords: holography, holographic interferometry, photomatrices with high spatial resolution, holography with an inclined reference beam, digital holography, Fourier transform

The purpose of this study was to assess the forest exploitation conditions of the central forestries of the Republic of Karelia and the Murmansk region. To do this, data were collected for 27 central forestries of the study region, representing 20 variables characterizing indicators of wood resources, natural production conditions and road infrastructure. The assessment of forest exploitation conditions was carried out on the basis of the developed system of indicators, which includes 5 indicators: the value of the exploitation fund; the representativeness of the territory to the natural conditions of growth of deciduous species and the level of allowable cutting area for softwood farming; representativeness of the territory with favorable natural and production conditions in the study region; size of allowable cuts for coniferous economy; and the quality of the road network. The indicators were factors extracted by the method of principal axes in the process of factor analysis. Factors explained 81.4% of the total variance of the 20 variables initially selected. The results of the study showed that two groups of forest areas are distinguished in terms of the average forest reserve: the forest areas of the Murmansk region, which are characterized by a low average reserve, and the forest areas of the Republic of Karelia. Four central forestries located in the southern part of the Republic of Karelia are distinguished by the level of reserves in the forests of deciduous tree species and the level of allowable cut for deciduous farming. The most favorable natural and production conditions are forest areas located in the southern part of the Republic of Karelia.

Keywords: logging, natural and production conditions, factor analysis, Karelia, Murmansk region, timber resources

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

The article discusses the importance of using computer modeling to analyze the technical and operational characteristics of products, identify possible failures. The paper presents the results of a study of the operational conditions of a threaded connection, and draws conclusions about the effectiveness of using the ANSYS software in the design of mechanical engineering products.

Keywords: threaded connection, modeling, innovative technologies, optimization, safety margin, performance characteristics, thread pitch, mechanical engineering

It is reported that recently, in many sectors of human activity, there has been an increasing interest in involving chatbots in company, organization or firm websites and in various applications to provide necessary assistance. This article deals with the current definitions of a chatbot and artificial intelligence. A chatbot is a computer program that imitates human speech using artificial intelligence. Artificial intelligence is a science and technology based on such disciplines as computer science, biology, psychology, linguistics, mathematics, and engineering. In the educational field, chatbots are useful for providing guidance and information about courses, admission processes and procedures, academic programs and academic services. However, these virtual assistants have limited mechanisms that could help the teaching and learning process. Attention is drawn to the fact that these mechanisms should be beneficial to all people involved. For this reason, the Voronezh State Industrial and Humanitarian College (GBPOU VO «VGPGK») was identified as the subject area in the development of a chatbot in the social network "VKontakte" for the page of an educational organization.The article considers the possibilities of using chatbots in the social network "VKontakte" for an educational organization focused on students and their parents. The article gives information about the development of the client part of the chatbot, namely the possibility of launching an electronic assistant using the page of the social network, the description of the data storage system for the chatbot and the server part. It is specially noted the variants of solutions for realization of a chatbot and the functioning of a chatbot.

Keywords: chatbot, website, server, client part, applications, social network, "VKontakte", mobile devices, artificial intelligence, computer program, information, educational sphere, message, training, data storage, electronic assistant

Three-dimensional printing (3DP) in building industry has a number of important advantages, such as creation of various geometric forms without the need for molds, the ability to create complex elements, the possibility of automation, speed and a low amount of waste, the use of innovative materials, construction in layers of different materials, and more. So, 3DP is an effort to put digital manufacturing into practice, enabling a direct transition from building design / modeling (BIM) to 3DP. One of the important limitations in 3DP is the materials. Because printing is done in layers, it is important to take into account the hardening time of the material and its ability to stick to create a uniform structure. Another problem is the tolerance of the material to different types of solidification: melting, pressing. That's why there are methods for combining iron or polymer reinforcement. There are combined methods: 3D printed elements are used as prefab elements to make the building process more effective. This industry is one of the fastest growing manufacturing technology sectors covers all markets from aerospace and healthcare to construction and consumer products. This article provides some aspects of application in construction, materials and their compositions, as well as examples of the use of 3DP at buildings, structures, etc.

Keywords: 3D technologies in civil engineering and construction, materials for 3DP, 3D concrete printing, concrete polymer reinforcement, dispersive reinforcement concrete