Pub Date : 2020-10-15DOI: 10.21122/2227-1031-2020-19-5-400-406
N. I. Zholud’
Determination of strategies for the formation of satellite cities of Minsk is the basis for the development of a polycentric model of the metropolitan agglomeration. On the basis of the comparative analysis of design solutions for master plans, a concept for improving the planning structure and functional organization of satellite cities has been proposed in the paper. The concept is to adapt their planning structure to one of the promising economic profiles (industrial, scientific and industrial, agrarian and industrial, tourism and recreation). In accordance with the concept, there are four main types of the planning structure of satellite cities that correlate with their city-forming specifics: an urbanized planning structure (type У) – an industrial city, an urbanized-natural structure (type УП) – a scientific-industrial city, a natural-urbanized structure (type ПУ) – agricultural and industrial city and a natural structure (type П) – tourist and recreational city. The selected period (20–30 years). While developing master plans, it is necessary to distinguish two main directions of transformation: transformation and development. The implementation of the first direction is provided by two strategies – fragmentation and defragmentation as well as four varieties of each strategy. Spatial development strategies are consolidation, vector growth, sector growth, radial growth. Particular attention is paid to the analysis of possible options for the placement of functional zones, depending on the distance of the city from the core city. Taking into account the identified strategies for spatial development and analysis of the location of satellite cities in the Minsk agglomeration, twelve planning models have been developed that can be used to create urban planning projects to improve the functional planning organization of settlements in the Minsk agglomeration.
{"title":"Planning Structure Transformation Strategies for Satellite Cities of the Minsk Agglomeration","authors":"N. I. Zholud’","doi":"10.21122/2227-1031-2020-19-5-400-406","DOIUrl":"https://doi.org/10.21122/2227-1031-2020-19-5-400-406","url":null,"abstract":"Determination of strategies for the formation of satellite cities of Minsk is the basis for the development of a polycentric model of the metropolitan agglomeration. On the basis of the comparative analysis of design solutions for master plans, a concept for improving the planning structure and functional organization of satellite cities has been proposed in the paper. The concept is to adapt their planning structure to one of the promising economic profiles (industrial, scientific and industrial, agrarian and industrial, tourism and recreation). In accordance with the concept, there are four main types of the planning structure of satellite cities that correlate with their city-forming specifics: an urbanized planning structure (type У) – an industrial city, an urbanized-natural structure (type УП) – a scientific-industrial city, a natural-urbanized structure (type ПУ) – agricultural and industrial city and a natural structure (type П) – tourist and recreational city. The selected period (20–30 years). While developing master plans, it is necessary to distinguish two main directions of transformation: transformation and development. The implementation of the first direction is provided by two strategies – fragmentation and defragmentation as well as four varieties of each strategy. Spatial development strategies are consolidation, vector growth, sector growth, radial growth. Particular attention is paid to the analysis of possible options for the placement of functional zones, depending on the distance of the city from the core city. Taking into account the identified strategies for spatial development and analysis of the location of satellite cities in the Minsk agglomeration, twelve planning models have been developed that can be used to create urban planning projects to improve the functional planning organization of settlements in the Minsk agglomeration.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"228 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2020-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80185568","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}
Pub Date : 2020-10-15DOI: 10.21122/2227-1031-2020-19-5-367-371
E. Y. Davydov, A. I. Bondarovich
When making welded joints, it is not always possible to press tightly elements to be joined before surfacing the weld. In normative documents on welded joints, the allowable gap between the elements to be connected can reach 3 mm when welding with a covered electrode and 2 mm when welding in shielded gases. At the same time the presence of a gap is not taken into account in the standards for calculation of welded joints. Experimental studies have been carried out to determine effect of the gap on the bearing capacity of the weld. Specimens have been made with welded joints of two types: for work in shear and pull-out. For the purpose of comparison, half of the specimens have been made without gaps, and the other half with gaps between the elements to be joined. The specimens have been made at the Minsk plant of technological metal structures, and their tests have been carried out in a research laboratory of the Belarusian National Technical University. Based on the results of the experiments, it has been concluded that the gaps between the elements to be joined significantly reduce the bearing capacity of the welded joints. In addition, inspection of fracture surfaces have shown that, in the presence of a gap, the cut surfaces of the weld pass along the fusion boundary of the base and deposited metals. It has been experimenttally established that the existing gap leads to a slight increase in the penetration depth. However, the latter factor does not compensate for the decrease in the bearing capacity of the welded joint due to the presence of a gap between the elements to be joined.
{"title":"To Calculation of Fillet Welds","authors":"E. Y. Davydov, A. I. Bondarovich","doi":"10.21122/2227-1031-2020-19-5-367-371","DOIUrl":"https://doi.org/10.21122/2227-1031-2020-19-5-367-371","url":null,"abstract":"When making welded joints, it is not always possible to press tightly elements to be joined before surfacing the weld. In normative documents on welded joints, the allowable gap between the elements to be connected can reach 3 mm when welding with a covered electrode and 2 mm when welding in shielded gases. At the same time the presence of a gap is not taken into account in the standards for calculation of welded joints. Experimental studies have been carried out to determine effect of the gap on the bearing capacity of the weld. Specimens have been made with welded joints of two types: for work in shear and pull-out. For the purpose of comparison, half of the specimens have been made without gaps, and the other half with gaps between the elements to be joined. The specimens have been made at the Minsk plant of technological metal structures, and their tests have been carried out in a research laboratory of the Belarusian National Technical University. Based on the results of the experiments, it has been concluded that the gaps between the elements to be joined significantly reduce the bearing capacity of the welded joints. In addition, inspection of fracture surfaces have shown that, in the presence of a gap, the cut surfaces of the weld pass along the fusion boundary of the base and deposited metals. It has been experimenttally established that the existing gap leads to a slight increase in the penetration depth. However, the latter factor does not compensate for the decrease in the bearing capacity of the welded joint due to the presence of a gap between the elements to be joined.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"92 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2020-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86675619","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}
Pub Date : 2020-10-15DOI: 10.21122/2227-1031-2020-19-5-413-420
A. О. Kolikov, G. P. Pastushkov
Metro Service has a huge impact on the development of urban transport infrastructure. The need to increase the efficiency of passenger transportation is caused by the rapid growth in passenger turnover as well as an increase in the distance from the outskirts of the city to the center. In connection with the need to develop a metro service network in Minsk city, which is confirmed by research in the area of passenger traffic in the main areas of the city, the CSM Bessac tunnel boring machine was purchased, which allows significantly to increase the speed of tunnel driving. The use of a mechanized tunnel boring machine in the traditional concept of the metro network construction, in which driving of tunnels is carried out after construction of stations, does not allow to use a shield with maximum economic efficiency due to the small extent of tunnels. There is also a need to build assembly-shield chambers and carry out works on disassembling and assembling the shield. The application of the new concept developed by Yu. S. Frolov and called “through driving” is actual in the conditions of the use of a mechanized tunnel boring machine. Its essence lies in the continuous driving of tunnels on the line section under construction and the consecutive construction of each station complex as the tunnel boring machine passes through it. To implement the concept of “through driving”, it is relevant to use a semi-closed construction method, in which the floor structure is constructed in an open way, and the other elements are closed. The available solutions of the metro stations constructed while using a semi-closed method of work have been analyzed in the paper. A detailed analysis has been carried out with due account of the adaptation to the construction conditions in Minsk, and the development of structural elements and assemblies of the platform area of the station, which is a two-cantilever vault with a developed transom part, resting on pile-columns of a circular cross section. Forces from the open ring of flexible tunnels lining are supported by a cantilever part of an arch and a bottom plate. The paper considers a design of a metro station, its main elements, their purpose and specificity of work, as well as optimization issues and the results of the design feasibility study.
{"title":"Single-Level Station Complex Structure for Application of Through Driving Construction Method","authors":"A. О. Kolikov, G. P. Pastushkov","doi":"10.21122/2227-1031-2020-19-5-413-420","DOIUrl":"https://doi.org/10.21122/2227-1031-2020-19-5-413-420","url":null,"abstract":"Metro Service has a huge impact on the development of urban transport infrastructure. The need to increase the efficiency of passenger transportation is caused by the rapid growth in passenger turnover as well as an increase in the distance from the outskirts of the city to the center. In connection with the need to develop a metro service network in Minsk city, which is confirmed by research in the area of passenger traffic in the main areas of the city, the CSM Bessac tunnel boring machine was purchased, which allows significantly to increase the speed of tunnel driving. The use of a mechanized tunnel boring machine in the traditional concept of the metro network construction, in which driving of tunnels is carried out after construction of stations, does not allow to use a shield with maximum economic efficiency due to the small extent of tunnels. There is also a need to build assembly-shield chambers and carry out works on disassembling and assembling the shield. The application of the new concept developed by Yu. S. Frolov and called “through driving” is actual in the conditions of the use of a mechanized tunnel boring machine. Its essence lies in the continuous driving of tunnels on the line section under construction and the consecutive construction of each station complex as the tunnel boring machine passes through it. To implement the concept of “through driving”, it is relevant to use a semi-closed construction method, in which the floor structure is constructed in an open way, and the other elements are closed. The available solutions of the metro stations constructed while using a semi-closed method of work have been analyzed in the paper. A detailed analysis has been carried out with due account of the adaptation to the construction conditions in Minsk, and the development of structural elements and assemblies of the platform area of the station, which is a two-cantilever vault with a developed transom part, resting on pile-columns of a circular cross section. Forces from the open ring of flexible tunnels lining are supported by a cantilever part of an arch and a bottom plate. The paper considers a design of a metro station, its main elements, their purpose and specificity of work, as well as optimization issues and the results of the design feasibility study.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"16 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2020-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82023828","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}
Pub Date : 2020-10-15DOI: 10.21122/2227-1031-2020-19-5-372-376
S. V. Bosakov, P. D. Skachok
Using the example of vertical displacements, it is shown that by combining a solution to the problem of determining vertical displacements from the action of four identical concentrated forces symmetrically applied to an elastic half-space and two identical concentrated forces symmetrically applied to an elastic quarter-space, one can obtain a solution about the action of one force on 1/8 of the elastic space with free edges. To find vertical displacements in an elastic half-space, the Boussinesq solution is used, and vertical displacements in an elastic quarter-space – an integral equation obtained by Ya. S. Uflyand to determine vertical displacements in the face of a homogeneous elastic isotropic quarter-space, for which a deformation modulus and Poisson’s ratio are constant. However, an integral equation of Ya. S. Uflyand is very inconvenient for practical use, therefore, in the paper, an approximate expression written in terms of elementary functions is proposed to find vertical displacements in the face of an elastic quarter-space from the action of a concentrated force. To obtain the latter, a special approximation method is used. The desired solution is also expressed in terms of elementary functions. In this case, an accurate calculation is obtained for an incompressible material with Poisson’s ratio 1/8 of the space n = 0.5. Since the solution is obtained in the case of a concentrated force acting on 1/8 of the elastic space, it is easy to find an expression for determining the vertical displacements of the edge of 1/8 of the elastic space from the action of any distributed load by integrating over the area of action of this load from the influence function, which is taken as required decision. Recommendations for improving the accuracy of calculations are offered. The described approach can also be used to determine the stress-strain of 1/8 of the space with both hingedly supported and free edges.
{"title":"Concentrated Force Action on 1/8 Homogeneous Isotropic Space","authors":"S. V. Bosakov, P. D. Skachok","doi":"10.21122/2227-1031-2020-19-5-372-376","DOIUrl":"https://doi.org/10.21122/2227-1031-2020-19-5-372-376","url":null,"abstract":"Using the example of vertical displacements, it is shown that by combining a solution to the problem of determining vertical displacements from the action of four identical concentrated forces symmetrically applied to an elastic half-space and two identical concentrated forces symmetrically applied to an elastic quarter-space, one can obtain a solution about the action of one force on 1/8 of the elastic space with free edges. To find vertical displacements in an elastic half-space, the Boussinesq solution is used, and vertical displacements in an elastic quarter-space – an integral equation obtained by Ya. S. Uflyand to determine vertical displacements in the face of a homogeneous elastic isotropic quarter-space, for which a deformation modulus and Poisson’s ratio are constant. However, an integral equation of Ya. S. Uflyand is very inconvenient for practical use, therefore, in the paper, an approximate expression written in terms of elementary functions is proposed to find vertical displacements in the face of an elastic quarter-space from the action of a concentrated force. To obtain the latter, a special approximation method is used. The desired solution is also expressed in terms of elementary functions. In this case, an accurate calculation is obtained for an incompressible material with Poisson’s ratio 1/8 of the space n = 0.5. Since the solution is obtained in the case of a concentrated force acting on 1/8 of the elastic space, it is easy to find an expression for determining the vertical displacements of the edge of 1/8 of the elastic space from the action of any distributed load by integrating over the area of action of this load from the influence function, which is taken as required decision. Recommendations for improving the accuracy of calculations are offered. The described approach can also be used to determine the stress-strain of 1/8 of the space with both hingedly supported and free edges.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"3 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2020-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76002457","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}
Pub Date : 2020-10-15DOI: 10.21122/2227-1031-2020-19-5-377-383
A. A. Dalidovskaya, V. Pastushkov
Today, there is an acute issue of ensuring the safe operation of buildings and structures located in the immediate vicinity of new construction. The process of performing works on the installation of load-bearing structures and their further operation can have a negative impact on already existing facilities. In this regard, the task of developing innovative methods and tools to ensure the safe operation of such structures as subway running tunnels is very urgent. To solve it, a reliable forecast of additional deformation and appointment of a complex of protective measures are required. In addition, much attention should be paid to the numerical modeling of the system “surface structures – protective measures – underground structures”. As an example of assessing the impact of new construction, namely, the erection of surface structures over existing underground ones, one can cite the construction of a transport interchange at the intersection of Nezavisimosty Avenue with Filimonov Street. As protective measures, a protective screen on bored piles has been used here, which made it possible to minimize significantly dynamic and static effects on the lining of tunnels and other underground structures of the subway. Effectiveness of protection application is confirmed by the result of monitoring the stress-strain state of running tunnel structures at all stages of traffic intersection construction. Protective measures and continuous monitoring of the stress-strain state in structures help to avoid accidents during construction and further operation.
{"title":"Protective Measures during Construction of Ground Structures over Existing Underground Structures","authors":"A. A. Dalidovskaya, V. Pastushkov","doi":"10.21122/2227-1031-2020-19-5-377-383","DOIUrl":"https://doi.org/10.21122/2227-1031-2020-19-5-377-383","url":null,"abstract":"Today, there is an acute issue of ensuring the safe operation of buildings and structures located in the immediate vicinity of new construction. The process of performing works on the installation of load-bearing structures and their further operation can have a negative impact on already existing facilities. In this regard, the task of developing innovative methods and tools to ensure the safe operation of such structures as subway running tunnels is very urgent. To solve it, a reliable forecast of additional deformation and appointment of a complex of protective measures are required. In addition, much attention should be paid to the numerical modeling of the system “surface structures – protective measures – underground structures”. As an example of assessing the impact of new construction, namely, the erection of surface structures over existing underground ones, one can cite the construction of a transport interchange at the intersection of Nezavisimosty Avenue with Filimonov Street. As protective measures, a protective screen on bored piles has been used here, which made it possible to minimize significantly dynamic and static effects on the lining of tunnels and other underground structures of the subway. Effectiveness of protection application is confirmed by the result of monitoring the stress-strain state of running tunnel structures at all stages of traffic intersection construction. Protective measures and continuous monitoring of the stress-strain state in structures help to avoid accidents during construction and further operation. ","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"29 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2020-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84669805","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}
Pub Date : 2020-08-05DOI: 10.21122/2227-1031-2020-19-4-311-319
A. S. Garkavenko, V. Mokritsky, O. Maslov, A. Sokolov
. Catastrophic degradation takes place in case of reaching critical values of laser radiation density power in semiconductor lasers with electronically pumped energy made from single crystals of some compounds. It has been accompanied by mechanical destruction of the surface at resonator ends, an irreversible decrease in radiation power and an increase in generation threshold. Moreover, during the catastrophic degradation of semiconductor lasers under the action of intrinsic radiation, significant changes in the crystal structure occur within the single crystal: dislocation density reaches a value more 1012–1015 cm–2. It has been shown that initial density of dislocations and critical power density of the intrinsic radiation are inversely proportional. Thus, the degradation process of semiconductor lasers is directly related to generation and multiplication of dislocations during laser operation. Mechanical destruction of a crystal lattice occurs at critical values of laser radiation power and dislocation density. To clarify the proposed mechanism for the degradation of semiconductor lasers, it is necessary to take into account an effect of dislocations on optical properties of semiconductors. Typically, this effect is considered as follows: dislocations cause an appearance of a local deformation field and, in addition, form space-charge regions that surround a dislocation core in the form of a charged tube. The paper proposes a model of the phenomenon under study: large stresses arise in the dislocation core, leading to a displacement of individual atoms and deformation of the crystal lattice. Lattice deformation in the dislocation core leads to a local change in the width of a forbidden band. This change value is about 10–2 eV for a screw dislocation and 10–1 eV for a boundary dislocation. The mechanism of this change is that aforementioned deformation leads to a multiple rupture of electronic bonds and an increase in the electron concentration in the dislocation core to approximately value 1018 cm–3. The developed analytical model of the degradation mechanism allows to perform selection of a semiconductor and estimation of a laser operating mode under conditions of increased radiation power.
{"title":"Nature of Degradation in Semiconductor Lasers with Electronic Energy Pumping. Theoretical Background","authors":"A. S. Garkavenko, V. Mokritsky, O. Maslov, A. Sokolov","doi":"10.21122/2227-1031-2020-19-4-311-319","DOIUrl":"https://doi.org/10.21122/2227-1031-2020-19-4-311-319","url":null,"abstract":". Catastrophic degradation takes place in case of reaching critical values of laser radiation density power in semiconductor lasers with electronically pumped energy made from single crystals of some compounds. It has been accompanied by mechanical destruction of the surface at resonator ends, an irreversible decrease in radiation power and an increase in generation threshold. Moreover, during the catastrophic degradation of semiconductor lasers under the action of intrinsic radiation, significant changes in the crystal structure occur within the single crystal: dislocation density reaches a value more 1012–1015 cm–2. It has been shown that initial density of dislocations and critical power density of the intrinsic radiation are inversely proportional. Thus, the degradation process of semiconductor lasers is directly related to generation and multiplication of dislocations during laser operation. Mechanical destruction of a crystal lattice occurs at critical values of laser radiation power and dislocation density. To clarify the proposed mechanism for the degradation of semiconductor lasers, it is necessary to take into account an effect of dislocations on optical properties of semiconductors. Typically, this effect is considered as follows: dislocations cause an appearance of a local deformation field and, in addition, form space-charge regions that surround a dislocation core in the form of a charged tube. The paper proposes a model of the phenomenon under study: large stresses arise in the dislocation core, leading to a displacement of individual atoms and deformation of the crystal lattice. Lattice deformation in the dislocation core leads to a local change in the width of a forbidden band. This change value is about 10–2 eV for a screw dislocation and 10–1 eV for a boundary dislocation. The mechanism of this change is that aforementioned deformation leads to a multiple rupture of electronic bonds and an increase in the electron concentration in the dislocation core to approximately value 1018 cm–3. The developed analytical model of the degradation mechanism allows to perform selection of a semiconductor and estimation of a laser operating mode under conditions of increased radiation power.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"34 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2020-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86440866","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}
Pub Date : 2020-08-05DOI: 10.21122/2227-1031-2020-19-4-280-287
F. I. Panteleenko, A. A. Danilov
The paper presents characteristics of the known classifications of surface shaping methods in mechanical engineering during mechanical and physical-technical processing; according to the classifications a surface shaping method is considered as a combination of methods for generating its producing lines – generatrix and guide – provided that the generation rate of the generatrix is higher than the guide. The advantages of constructing a classification and a formalized description of surface shaping methods have been shown in the paper; each of them represents a combination of surface formation methods in cross section and in length, regardless of generation speed for generatrix and guide lines. This increases information content of the description for a shaping method which is important for comparing methods of shaping surfaces and synthesis of schemes for their processing in the functional design of the machine. The paper has revealed the fact that in comparison with the well-known classification of A. A. Fedotenka it is an expedient to introduce methods of bending, intermittent track and intermittent rolling, as well as combined methods combining advantages of their basic methods which expand the synthesis of progressive processing schemes for profile surfaces. The introduction of the methods has been made in many basic methods of generating production lines (copying, following, touching and rolling). Based on the expanded set of basic methods and the accepted principle of presenting the methods of shaping profile surfaces, their classification has been developed as the basis for systematization and synthesis of known and possible shaping methods. The paper considers examples of rational shaping method synthesis based on the proposed classification and progressive processing schemes for profile moment-transmitting surfaces on the basis of synthesis examples. In particular, the use of an envelope method instead of the applied rolling method has made it possible to simplify significantly a tool design, to increase its versatility and accuracy in formation of moment-transmitting surfaces with a profile in the form of a Relo triangle.
介绍了机械工程中机械加工和物理技术加工中已知的几种表面成形方法的特点;根据分类，曲面成形方法被认为是生成其生产线的方法——母线和导轨的组合，前提是母线的生成速率高于导轨。本文指出了对曲面成形方法进行分类和形式化描述的优点;无论母阵和导线的生成速度如何，它们在截面和长度上都代表了表面形成方法的组合。这增加了一种成形方法描述的信息量，这对于在机器的功能设计中比较表面成形方法及其加工方案的综合是重要的。本文揭示了与众所周知的A. A. Fedotenka分类相比，引入弯曲法、间歇轨迹法和间歇滚压法以及结合其基本方法优点的组合方法是一种方便的方法，扩大了型材表面级进加工方案的综合。介绍了许多生成生产线的基本方法(复制、跟随、触摸和滚动)。基于扩展的基本方法集和公认的轮廓表面成型方法的呈现原则，它们的分类已经发展成为系统化和综合已知和可能的成型方法的基础。在综合实例的基础上，给出了基于所提出的轮廓力矩传递曲面分类和递进加工方案的合理成形方法综合实例。特别是，包络线法代替滚压法的使用，大大简化了刀具的设计，提高了其在形成具有Relo三角形轮廓的力矩传递曲面时的通用性和准确性。
{"title":"Классификация методов формообразования и синтез на ее основе схем обработки профильных моментопередающих поверхностей","authors":"F. I. Panteleenko, A. A. Danilov","doi":"10.21122/2227-1031-2020-19-4-280-287","DOIUrl":"https://doi.org/10.21122/2227-1031-2020-19-4-280-287","url":null,"abstract":"The paper presents characteristics of the known classifications of surface shaping methods in mechanical engineering during mechanical and physical-technical processing; according to the classifications a surface shaping method is considered as a combination of methods for generating its producing lines – generatrix and guide – provided that the generation rate of the generatrix is higher than the guide. The advantages of constructing a classification and a formalized description of surface shaping methods have been shown in the paper; each of them represents a combination of surface formation methods in cross section and in length, regardless of generation speed for generatrix and guide lines. This increases information content of the description for a shaping method which is important for comparing methods of shaping surfaces and synthesis of schemes for their processing in the functional design of the machine. The paper has revealed the fact that in comparison with the well-known classification of A. A. Fedotenka it is an expedient to introduce methods of bending, intermittent track and intermittent rolling, as well as combined methods combining advantages of their basic methods which expand the synthesis of progressive processing schemes for profile surfaces. The introduction of the methods has been made in many basic methods of generating production lines (copying, following, touching and rolling). Based on the expanded set of basic methods and the accepted principle of presenting the methods of shaping profile surfaces, their classification has been developed as the basis for systematization and synthesis of known and possible shaping methods. The paper considers examples of rational shaping method synthesis based on the proposed classification and progressive processing schemes for profile moment-transmitting surfaces on the basis of synthesis examples. In particular, the use of an envelope method instead of the applied rolling method has made it possible to simplify significantly a tool design, to increase its versatility and accuracy in formation of moment-transmitting surfaces with a profile in the form of a Relo triangle.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"61 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2020-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83100538","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}
Pub Date : 2020-08-05DOI: 10.21122/2227-1031-2020-19-4-271-279
К. Шелег, доц. А. Н. Жигалов, асп. Д. Д. Богдан, V. Sheleg, A. N. Jigalov, D. D. Bogdan
To increase the durability of metal-cutting carbide plates operating during in harsh technological conditions with impact load, an aerodynamic sound hardening method has been developed that can increase a life of carbide tools up to 3.7 times with a small added cost. The wear of plates hardened by the aerodynamic sound method, after 100 min of cutting, is 1.12–1.7 times less than their un-strengthened analogues. A coating on metal carbide plates does not have a prevailing value when a tool is working with impact loads. While working with impact loads viscosity of an internal plate structure occurs the greatest influence on increasing resistance. For metal-cutting carbide plates during interrupted cutting with significant impact loads, a method of aerodynamic sound hardening is more effective than a coating method, not only in terms of tool performance, but also in the cost of completion itself. Empirical dependences of wear on the rear surface of carbide plates hardened by a aerodynamic sound method and plates with PVD coatings have been obtained in the form of approximation by polynomials of the 5th and 2nd degrees, which are convenient to use in a production environment. It has been revealed the higher carbide plate strength in bending leads to less influence of the method of aerodynamic sound hardening on the increase in wear resistance. So, taking into account the fact that for ВК8-base the ultimate bending strength is 1666 MPa, and for T5K10 it is 1421 MPa, wear reduction after hardening by the aerodynamic sound method for ВП3115-plates with ВК base is 11.5 %, while for ВП3225 – plates with ТК-base – 27.1 %.
{"title":"Study on Effect of Aerodynamic Sound Hardening for Wear of Coated Carbide Metal Plates","authors":"К. Шелег, доц. А. Н. Жигалов, асп. Д. Д. Богдан, V. Sheleg, A. N. Jigalov, D. D. Bogdan","doi":"10.21122/2227-1031-2020-19-4-271-279","DOIUrl":"https://doi.org/10.21122/2227-1031-2020-19-4-271-279","url":null,"abstract":"To increase the durability of metal-cutting carbide plates operating during in harsh technological conditions with impact load, an aerodynamic sound hardening method has been developed that can increase a life of carbide tools up to 3.7 times with a small added cost. The wear of plates hardened by the aerodynamic sound method, after 100 min of cutting, is 1.12–1.7 times less than their un-strengthened analogues. A coating on metal carbide plates does not have a prevailing value when a tool is working with impact loads. While working with impact loads viscosity of an internal plate structure occurs the greatest influence on increasing resistance. For metal-cutting carbide plates during interrupted cutting with significant impact loads, a method of aerodynamic sound hardening is more effective than a coating method, not only in terms of tool performance, but also in the cost of completion itself. Empirical dependences of wear on the rear surface of carbide plates hardened by a aerodynamic sound method and plates with PVD coatings have been obtained in the form of approximation by polynomials of the 5th and 2nd degrees, which are convenient to use in a production environment. It has been revealed the higher carbide plate strength in bending leads to less influence of the method of aerodynamic sound hardening on the increase in wear resistance. So, taking into account the fact that for ВК8-base the ultimate bending strength is 1666 MPa, and for T5K10 it is 1421 MPa, wear reduction after hardening by the aerodynamic sound method for ВП3115-plates with ВК base is 11.5 %, while for ВП3225 – plates with ТК-base – 27.1 %.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"36 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2020-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87406549","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}
Pub Date : 2020-08-05DOI: 10.21122/2227-1031-2020-19-4-349
A. Czerepicki, W. Choromański, M. Kozłowski, A. Kazinski
The electric bus is an ecological means of transport. Its operation reduces the negative impact on the environment. The transition to electric urban transport is in line with the concept of sustainable development of the European Union and the Polish “Act on Electromobility and Alternative Fuels”. Today, on the streets of Polish cities, electric buses are increasingly replacing diesel-powered vehicles. The electrification of the bus fleet requires the establishment of an appropriate infrastructure for charging vehicle batteries. Electric chargers are placed at the end stops of the communication lines. When the bus stops at the end of the route, it is possible to partially recharge the energy consumed. The amount of recharged energy depends on many factors, such as the power of the charger, bus stop time, possible waiting time for a free charger, etc. In the event of incomplete replenishment of the consumed energy, the completion of subsequent courses may be endangered. The article proposes an approach to the analysis of the process of charging electric buses at the end stops of the route, taking into account the characteristics of the vehicle battery, the intensity of vehicle traffic, the characteristics of stationary chargers and its quantity. The proposed approach uses queue theory to describe the process of bus charging. The result of the research is the estimation of the use of the chargers in different configurations and the estimation of the state of charge of the bus battery for selected timetables.
{"title":"Analysis of the Problem of Electric Buses Charging in Urban Transport","authors":"A. Czerepicki, W. Choromański, M. Kozłowski, A. Kazinski","doi":"10.21122/2227-1031-2020-19-4-349","DOIUrl":"https://doi.org/10.21122/2227-1031-2020-19-4-349","url":null,"abstract":"The electric bus is an ecological means of transport. Its operation reduces the negative impact on the environment. The transition to electric urban transport is in line with the concept of sustainable development of the European Union and the Polish “Act on Electromobility and Alternative Fuels”. Today, on the streets of Polish cities, electric buses are increasingly replacing diesel-powered vehicles. The electrification of the bus fleet requires the establishment of an appropriate infrastructure for charging vehicle batteries. Electric chargers are placed at the end stops of the communication lines. When the bus stops at the end of the route, it is possible to partially recharge the energy consumed. The amount of recharged energy depends on many factors, such as the power of the charger, bus stop time, possible waiting time for a free charger, etc. In the event of incomplete replenishment of the consumed energy, the completion of subsequent courses may be endangered. The article proposes an approach to the analysis of the process of charging electric buses at the end stops of the route, taking into account the characteristics of the vehicle battery, the intensity of vehicle traffic, the characteristics of stationary chargers and its quantity. The proposed approach uses queue theory to describe the process of bus charging. The result of the research is the estimation of the use of the chargers in different configurations and the estimation of the state of charge of the bus battery for selected timetables.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"71 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2020-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90381012","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}
Pub Date : 2020-06-05DOI: 10.21122/2227-1031-2020-19-3-230-240
M. K. Pshembaev, Ya. N. Kovalev, V. Yaglov, V. V. Girinsky
There are several methods for prevention of winter slippery on the roads – frictional, thermal, chemical, combined and structural. The friction method of combating slippery has found quite wide application. The method is based on increasing a wheel grip with iced road. Sand, slag, screening of stone materials and friction materials subjected to heating are used as a friction raw material. A thermal method is divided in conductive and convective according to a surface heating type in which a pavement is heated from below (electric heating) or from above (with a heat stream). Disadvantages of this method are its high cost when using thermal jets and harmful effects of high temperatures on a road surface. Nowadays a chemical method is considered as the most popular one to combat winter slippery. Treatment with solid or liquid reagents is provided in order to prevent slipping on the road surface or removing ice from it. The principle of their action is to lower a freezing temperature of the solution on the surface of the roadway. The fight against winter slippage is mainly carried out in a combined way by sprinkling roads with a sand and salt mixture. Currently, there is a need to completely or partially abandon the use of chlorides in the fight against winter slippery. In this case, the most promising direction is to prevent icing by creating coatings for roads with anti-icing properties that is introduction of anti-icing reagents in the composition of the road surface (construction method). This method makes it possible to increase cost of a finished road surface.
{"title":"Methods for Prevention of Winter Slippery","authors":"M. K. Pshembaev, Ya. N. Kovalev, V. Yaglov, V. V. Girinsky","doi":"10.21122/2227-1031-2020-19-3-230-240","DOIUrl":"https://doi.org/10.21122/2227-1031-2020-19-3-230-240","url":null,"abstract":"There are several methods for prevention of winter slippery on the roads – frictional, thermal, chemical, combined and structural. The friction method of combating slippery has found quite wide application. The method is based on increasing a wheel grip with iced road. Sand, slag, screening of stone materials and friction materials subjected to heating are used as a friction raw material. A thermal method is divided in conductive and convective according to a surface heating type in which a pavement is heated from below (electric heating) or from above (with a heat stream). Disadvantages of this method are its high cost when using thermal jets and harmful effects of high temperatures on a road surface. Nowadays a chemical method is considered as the most popular one to combat winter slippery. Treatment with solid or liquid reagents is provided in order to prevent slipping on the road surface or removing ice from it. The principle of their action is to lower a freezing temperature of the solution on the surface of the roadway. The fight against winter slippage is mainly carried out in a combined way by sprinkling roads with a sand and salt mixture. Currently, there is a need to completely or partially abandon the use of chlorides in the fight against winter slippery. In this case, the most promising direction is to prevent icing by creating coatings for roads with anti-icing properties that is introduction of anti-icing reagents in the composition of the road surface (construction method). This method makes it possible to increase cost of a finished road surface.","PeriodicalId":42375,"journal":{"name":"Science & Technique","volume":"18 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2020-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89968721","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}
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