Science & Technique最新文献

{"title":"Recuperative Heat Exchanger-Utilizer Thermodynamic Modes in Low Capacity Supply-and-Exhaust Ventilation Unit","authors":"V. A. Zafatayeu, T. I. Karaliova","doi":"10.21122/2227-1031-2022-21-4-297-313","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-4-297-313","url":null,"abstract":"The increase in the thermal protection level of the existing buildings enclosing structures, due to the need to comply with the current norms of building heat engineering requirements, leads to increasing in the part of heat losses in the thermal balance of a building due to infiltration and exhaust ventilation operation. After exhaustion of the possibilities for the implementation of technical measures to reduce energy costs by changing in volumetric planning solutions and insulating building envelopes further decreasing heat consumption level should be associated with the use of the secondary and renewable resources potential. The paper presents the results of assessing the technical and economic feasibility of using the exhaust air thermal potential for heating the supply air in the forced supply-and-exhaust ventilation system of a building taking as a low-capacity unit as an example. For a counterflow air-to-air recuperative type heat utilizer finned with ribbed heat pipes in the form of a plurality of continuous sheets, the influence of changes in the physical properties of the exhaust air during the phase transition of the water vapor contained in it into a liquid state on the heat exchanger-utilizer performance and characteristics of its efficiency has been established. The conditions of heat exchange are determined (without condensate, with condensate in the part of the heat exchanger-utilizer, with condensate in the entire heat exchanger-utilizer and with the risk of icing) in the supply air temperature range from (–26) to (+8) °C for three variants of its operation with a balance of the nominal amount of exhaust and supply air and with two variants of imbalance. Variants with imbalances have been investigated in order to find possible combinations of supply and exhaust air temperatures, at which there would be no phase transition of water vapor in the exhaust air flow to the liquid state in the entire volume of the heat utilizer, which would eliminate the need for measures to collect and remove condensate and preventing it from freezing.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"119 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132275040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reinforced Concrete Posts Made by Long-Line Formwork-Free Shaping for 0.4–10 kV Overhead Line Supports","authors":"P. Mirzaev, Z. P. Shamansurova","doi":"10.21122/2227-1031-2022-21-4-314-322","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-4-314-322","url":null,"abstract":"When using the technology of long-line formwork-free shaping for the manufacture of reinforced concrete structures, industrial engineering can be conducted in accordance with the requirements of modern regulatory documents. This allows projects to be developed individually, and production lines can be readjusted in a short time in accordance with emerging needs. In this regard, the possibility of using reinforced concrete posts produced by the technology of long-line formwork-free shaping for 0.4-10 kV overhead line supports is being considered. The designs of such supports are developed on the standard basis of the product range. The problem of establishing the minimum number (two) of cross-sections with different geometric dimensions for all brands of the offered posts is solved, subject to the operational requirements and technological specifications of production. The cross-sections of the proposed posts represent trapeziums, with the dimensions of the upper bases smaller than the dimensions of the lower bases in order to maintain the shape of the freshly formed concrete body of the posts made using long-line formwork-free shaping technology. For posts up to 11.0 m long, a solid cross-section with trapezoid edges is proposed: h = 245 mm; b = 150 mm (an upper base); b1 = 180 mm (a lower base). In the middle part of the cross-section of posts with a length of 11.0 to 16.4 m there is a cavity along the entire length of the posts. Cross-sectional dimensions of such posts are h = 300 mm; b = 205 mm, b1 = 235 mm. Long-line formwork-free shaping technology provides for the reinforcement of prestressed structures with high-strength wire or rope reinforcement. The proposed posts are rein-forced with 5Вр1400 rods, therefore, during their operation, the formation of cracks in the tensile zone of concrete is not fore-seen. The rods are located in groups at all corner sections along the cross-section of the post with an equal number of rods in each group, taking into account the technological features of the long-line formwork-free shaping. For the proposed cross-section of hollow posts, produced by long-line formwork-free shaping for 0.4–10 kV overhead line supports, a patent for autility model has been obtained from the Agency for Intellectual Property of Uzbekistan. Qualitative characteristics of the posts for overhead line supports are low material consumption, versatility, manufacturability, innovation, which lies in the fact that their implementation is associated with the design, manufacture and testing of experimental products for use by specific consumers, i. e. with the commercialization.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116182167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Technology for Production of MSF-fuel – Direction Providing Transition to Circular Economy","authors":"B. Khroustalev, A. N. Pekhota, R. N. Vostrova, E. A. Pekhota","doi":"10.21122/2227-1031-2022-21-4-340-348","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-4-340-348","url":null,"abstract":"The paper presents the technology of multi-component briquetting of solid fuel (MSF-fuel) developed by the authors, which makes it possible to reduce economic losses from the non-use of combustible waste from industrial and municipal human activities. The issues of energy and resource saving, rational use of natural and secondary resources in accordance with the National Strategy for Sustainable Development of the Republic for the period up to 2035 are considered in the paper. The concept, structure and principles of the circular economy are analyzed. The paper provides characteristics of the main areas of use and processing of waste that have not found application in traditional technologies and energy. Some aspects of the conducted research on the production of multicomponent solid fuels are presented in the paper. The technology of briquetting wet mixtures with the addition of various binders, including combustible waste, is described, taking into ac-count the factors that affect the performance of the briquetting plant and the density of the fuel. Various ratios of the components of briquetting fuel have been analyzed and the compositions are determined, at which the best production, consumer and environmental indicators are analyzed. The paper studies the energy and physicochemical characteristics of the produced multicomponent fuel. Algorithms for selecting fuel components have been developed. The results obtained can be used to solve problems of rational use of combustible industrial waste by producing a multicomponent solid fuel that meets the established energy and environmental requirements.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133419918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improvement of Calculation Technique for Flexible Orthotropic Plates on Elastic Base. Part 2. Calculation Results","authors":"O. Kozunova","doi":"10.21122/2227-1031-2022-21-4-290-296","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-4-290-296","url":null,"abstract":"The proposed paper is a continuation of the author's theoretical work presented earlier in the development of the theory and methodology for calculating flexible orthotropic reinforced concrete plates on an elastic foundation, taking into account the physical nonlinearity of the plate material. The paper presents numerical results of elastic and nonlinear calculations of an isolated rectangular orthotropic plate on an elastic foundation, modeled by an elastic homogeneous isotropic layer rigidly connected to a non-deformable foundation under the action of an external static load, taking into account the own weight of the reinforced concrete plate. The change in its stiffness at the time of cracking and further active opening of cracks has been taken into account in the calculation of the structure under study. The nonlinear calculation of the studied structure takes into account the change in its rigidity at the time of cracking and further active crack opening. The calculation of a flexible orthotropic plate on an elastic foundation in a nonlinear formulation is performed iteratively by the method of B. N. Zhemochkin. A mixed method of structural mechanics has been used to determine the coefficients of canonical equations and free terms. At the first iteration, the reinforced concrete plate is calculated as linearly elastic, homogeneous, and orthotropic; at the subsequent ones – as linearly elastic, inhomogeneous, and orthotropic at each Zhemochkin site. Camber plates with a clamped normal in the primary system of mixed method due to the action of a concentrated force are determined by the Ritz method when the deflections were represented as a power polynomial in a new original expression that has been proposed for the first time in the Part 1 of the paper. The solution algorithm has been implemented using the Wolfram Mathematica 11.3 computer program. Numerical and graphical results of elastic and non-linear calculations of sediment concrete road plate, contact stresses and bending moment diagrams on the plate are presented in the paper.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121697907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Durability of Concrete under Combined Impact Environment and Mechanical Load: Analysis of Experimental Studies","authors":"S. Leonovich, E. E. Shalyi, D. Litvinovskiy, A. V. Stepanova","doi":"10.21122/2227-1031-2022-21-4-269-280","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-4-269-280","url":null,"abstract":"Today, there are several methods for predicting the durability of reinforced concrete structures. In most cases, one of the dominant destruction processes is taken into account – either carbonization or chloride penetration. Experimental results and field observations show that this is an unrealistic approach. Therefore, it is necessary to develop a method for determining the durability of concrete under combined impacts, i. e. with the penetration of chlorides into it and mechanical load. The paper describes in detail an experimental method for studying the effect of mechanical load on the penetration of chlorides into the pore space of cement-based materials. A test method is presented that makes it possible to determine realistic diffusion coefficients of chloride ions in concrete under compressive or tensile stress. As a result of the experiments carried out, it has been determined that the combination of mechanical loads and environmental influences can be much more significant than just environmental influence without the influence of mechanical loading. In fact, the service life of reinforced concrete structures depends on many possible combinations of mechanical loads and environmental influences, including freeze-thaw cycles. Thus, cracks formed during freeze-thaw cycling should be taken into account in tests of combined environmental and mechanical stress in order to better understand and systematically describe the effect of such exposure on the durability of concrete. For reliable prediction of the service life of reinforced concrete structures, it is also necessary to take into account the influence of the applied cyclic stress.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132694745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improving the Efficiency of Information Application in the Organization of Passenger Transportation in Cities","authors":"D. Kapskiy, S. S. Semchenkov, O. Larin","doi":"10.21122/2227-1031-2022-21-4-323-330","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-4-323-330","url":null,"abstract":"The problem of organizing passenger transportation in cities is becoming more and more important every day. The situation is aggravated by the fact that the spontaneous growth of motorization leads to a drop in the capacity of streets, environmental pollution, destruction of ecosystems, and an increase in social tension. It became obvious that the creation of cities convenient for life is impossible without a system of route passenger transport. And here, improvement of the quality of passenger transportation in cities by increasing the efficiency of using the information necessary to manage the transportation process is of particular relevance. There is a need to create a unified information space in the field of transportation, involving all participants in the process. This, in turn, will help to provide reliable information to users (passengers) of route passenger transport, increase its reliability and passengers' trust in it. An important role here is played by the information sup-port of the transportation management process with the choice of the correct model for collecting reliable information about the movement of route vehicles and its correct use, which will lead to an increase in the reliability of the route passenger transport, and the provision of open reliable information about the movement of route vehicles will contribute to increasing user confidence in route passenger transport and at the same time discipline carriers and operators.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134023336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of Public Transport Fare Payment Systems in the Republic of Belarus","authors":"K. V. Siniutsich","doi":"10.21122/2227-1031-2022-21-4-349-356","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-4-349-356","url":null,"abstract":"The Republic of Belarus uses traditional and modern systems of fare payment for public passenger transport. In the traditional system, paper tickets are used as proof of payment; such a system is common in all settlements of the country. Electronic tickets generated in mobile applications of various electronic systems, on physical media – contactless smart cards, as well as records of relevant transactions from bank card accounts are used in modern fare systems to confirm payment for a transport service. Both single trips and multiple travel tickets can be recorded in the form of an electronic ticket or an electronic entry on the contactless smart cards. The paper proposes measures aimed at increasing the level of payback of public passenger transport, analyzes the volume of passenger traffic for 2016–2020, the decisions of local authorities in force in the cities of Belarus that establish regulatory and cost indicators for fares in public passenger transport. The comparison of modern fare payment systems implemented in cities is carried out. TapXphone and T-PAY systems are recommended for distribution on public passenger transport in Belarusian cities on the basis of the comparison of the positive аnd negative aspects of the functioning of electronic fare collection systems from the position of a passenger and a carrier.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134160450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Expert Component as Element of Content Strategy of Industrial Enterprise","authors":"V. A. Malaichuk","doi":"10.21122/2227-1031-2022-21-3-257-264","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-3-257-264","url":null,"abstract":"Internet marketing in the industrial market has a number of features and differs from that in the consumer market. The first is characterized by specialized and personalized approaches, as well as it must take into account the long cycle of the transaction, and the presence of a large number of decision makers. Marketers at industrial enterprises must have a range of knowledge about the market and industry trends, possess information about the organization of procurement processes and the operation of distribution channels, and be able to build a communication process with a certain type of customer. The paper presents methods for online promotion of industrial products and a study of the features of choosing of internet marketing tools for industrial enterprises. The main idea of the paper is to highlight the expert component for such enterprises as the main tool for communication with customers. To solve this problem, the internet marketing tools of an industrial enterprise has been considered and the expert component in its content strategy has been shown, approaches to the systematization of internet marketing tools have been studied. In the course of the study, general scientific methods have been used: analysis, synthesis, generalization. The result of the research is a model of product promotion in the logic of the industrial consumer's journey, which is based on the connection of the consumer's journey map with internet marketing tools.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122744212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"About One Variational Problem, Leading to а Biharmonic Equation, and about the Approximate Solution of the Main Boundary Value Problem for this Equation","authors":"I. Meleshko, P. G. Lasy","doi":"10.21122/2227-1031-2022-21-3-236-241","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-3-236-241","url":null,"abstract":". Many important questions in the theory of elasticity lead to a variational problem associated with a biharmonic equation and to the corresponding boundary value problems for such an equation. The paper considers the main boundary value problem for the biharmonic equation in the unit circle. This problem leads, for example, to the study of plate deflections in the case of kinematic boundary conditions, when the displacements and their derivatives depend on the circular coordinate. The exact solution of the considered boundary value problem is known. The desired biharmonic function can be represented explicitly in the unit circle by means of the Poisson integral. An approximate solution of this problem is sometimes foundusing difference schemes. To do this, a grid with cells of small diameter is thrown onto the circle, and at each grid node all partial derivatives of the problem are replaced by their finite-difference relations.  As a result, a system of linear algebraic equations arises for unknown approximate values of the biharmonic function, from which they are uniquely found. The disadvantage of this method is that the above system is not always easy to solve. In addition, we get the solution not at any point of the circle, but only at the nodes of the grid. For real calculations and numerical analysis of solutions to applied problems, the authors have constructed its unified analytical approximate representation on the basis of the known exact solution of the boundary value problem while using logarithms. The approximate formula has a simple form and can be easily implemented numerically. Uniform error estimates make it possible to perform calculations with a given accuracy. All coefficients of the quadrature formula for the Poisson integral are non-negative, which greatly simplifies the study of the approximate solution. An analysis of the quadrature sum for stability is carried out. An example of solving a boundary value problem is considered. ","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124239433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Application of Flow Theory Relations for Solving Problems of Steady-State Crack Growth","authors":"M. Hundzina, O. V. Yuhnovskaya","doi":"10.21122/2227-1031-2022-21-3-229-235","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-3-229-235","url":null,"abstract":"To represent local displacement fields in the problem of the steady-state growth of a crack, which contains a plate of incompressible material, the strain intensity formula is used in the form of a polynomial of the second degree. The case of plane deformation for an elastoplastic material is considered. The solution is obtained by the method of asymptotic expansions. Numerical analysis is carried out for the first term of the expansion. The aim of the work is the process of obtaining analytical solutions to applied problems of the theory of plasticity: finding the components of stress and strain tensors. The paper considers a variant of the method of asymptotic expansions and its application for the problem of the distribution of the stress-strain state in an elastoplastic specimen with a crack. The method of asymptotic expansions has some advantages over the numerical approach in studying the stress-strain state in the vicinity of a crack. It allows to establish exact quantitative relationships between the radial component, the angle, and the components of the stress and strain tensor. Another advantage of this method is the possibility of compiling the mechanical characteristics of an object at the design stage. A system of differential equations has been developed that contains V0 and its derivatives up to the third order. An example of stress distribution in the vicinity of a crack tip in a steel sample, obtained in a computer system by a numerical method, is given. The deformation diagram has been constructed for the material steel 40. The research results can be used to construct stress and strain fields in the vicinity of a crack, as well as to predict the further direction of crack development.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134348667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}