Pub Date : 2022-12-09DOI: 10.21122/2227-1031-2022-21-6-473-479
A. A. Bagdun, V. L. Solomakho
The paper proposes a set of technical tools for solving the problem of ensuring the uniformity of measurements of micro- and nanoparticles. To do this, it is necessary to ensure the traceabilityof particle size measurements to a unit of length – a meter, as well as equivalent diameters used in measurements in various dispersed media (aerosols and suspensions). To ensure traceability of particle diameter measurements to the meter, it is proposed to use a nanomeasuring machine with an atomic force microscope as a probing system. The paper presents a diagram of the measuring system, describes the principle of operation of the machine and the method for measuring particle sizes. The main alleged sources of errors in particle measurement by this method are also identified. To ensure the traceability of measurements of the hydrodynamic diameter of nanoparticles, which characterizes particles in a liquid (suspension), it is proposed to use a nanoparticle size analyzer that implements the method of dynamic light scattering. The scheme of the analyzer with a description of the principle of measuring the size of nanoparticles by the method of dynamic light scattering is presented in the paper. The scheme of the column of the analyzer of the differential electrical mobility of particles is presented to ensure the traceability of measurements of their diameter, which is equivalent in electrical mobility. Diameter is usually used to characterize particles in the aerosol state. A diagram of an analyzer for the differential electric mobility of particles is given with a description of the operating principle, a formula for calculating the particle diameter is derived.
{"title":"Methods and Technical Means for Ensuring Uniformity of Nanoparticle Size Measurements","authors":"A. A. Bagdun, V. L. Solomakho","doi":"10.21122/2227-1031-2022-21-6-473-479","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-6-473-479","url":null,"abstract":"The paper proposes a set of technical tools for solving the problem of ensuring the uniformity of measurements of micro- and nanoparticles. To do this, it is necessary to ensure the traceabilityof particle size measurements to a unit of length – a meter, as well as equivalent diameters used in measurements in various dispersed media (aerosols and suspensions). To ensure traceability of particle diameter measurements to the meter, it is proposed to use a nanomeasuring machine with an atomic force microscope as a probing system. The paper presents a diagram of the measuring system, describes the principle of operation of the machine and the method for measuring particle sizes. The main alleged sources of errors in particle measurement by this method are also identified. To ensure the traceability of measurements of the hydrodynamic diameter of nanoparticles, which characterizes particles in a liquid (suspension), it is proposed to use a nanoparticle size analyzer that implements the method of dynamic light scattering. The scheme of the analyzer with a description of the principle of measuring the size of nanoparticles by the method of dynamic light scattering is presented in the paper. The scheme of the column of the analyzer of the differential electrical mobility of particles is presented to ensure the traceability of measurements of their diameter, which is equivalent in electrical mobility. Diameter is usually used to characterize particles in the aerosol state. A diagram of an analyzer for the differential electric mobility of particles is given with a description of the operating principle, a formula for calculating the particle diameter is derived.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"159 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122034316","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 : 2022-12-09DOI: 10.21122/2227-1031-2022-21-6-455-463
B. I. Piatrouski, A. L. Paliakou, V. A. Misnikou, M. G. Shafikau
The third potash seam of the Starobinsky deposit is mainly mined using the layered mining technology. The essence of the technology lies in the advance excavation of the 4th sylvinite layer by the uppere lava and the joint excavation of layers 2, 2–3 and 3 by the lagging lower lava under the protection of the interlayer pack of rock salt 3–4 (ceiling) left in the goaf. The thickness of the ceiling in accordance with the requirements of the regulatory document should be at least 0.8 m. At the same time, in the mine field of the mine of the Third Mine Administration, there are areas with a ceiling thickness reduced to 0.66–0.70 m. The purpose of the author’s research was to determine the possibility of safe mining of the Third potash seam using the layered mining technology with a reduced thickness of the ceiling. In the course of a full-scale experiment, the geological structure and strength properties of the rocks of the ceiling, its stability in the bottomhole space and the intensity of loading of the bottomhole lining of the lower lavas have been studied in the paper. The research methods also included the analysis of literary sources and statistical processing of the obtained data. It has been established that a decrease in the thickness of the ceiling by 0.10–0.14 m from the required one does not have a significant effect on its strength, while it remains stable in the near-bottom space of the lower longwalls. The main indicators of the manifestation of rock pressure in the studied lower longwalls – the rate of increase of the bottomhole lining in the stope cycles and the lowering of the roof in the bottomhole space – did not exceed the similar indicators in the longwalls with the required thickness of the ceiling. The obtained data indicate the possibility of safemining of the Third potash seam using the layered excavation technology with the thickness of the interlayer rock salt pack 3–4 not less than 0.66 m. In this case, the bearing capacity of the bottomhole lining should be at least 550 kN/m2.
{"title":"Layered Excavation of the Third Potash Seam with Reduced Thickness of Interlayer Ceiling","authors":"B. I. Piatrouski, A. L. Paliakou, V. A. Misnikou, M. G. Shafikau","doi":"10.21122/2227-1031-2022-21-6-455-463","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-6-455-463","url":null,"abstract":"The third potash seam of the Starobinsky deposit is mainly mined using the layered mining technology. The essence of the technology lies in the advance excavation of the 4th sylvinite layer by the uppere lava and the joint excavation of layers 2, 2–3 and 3 by the lagging lower lava under the protection of the interlayer pack of rock salt 3–4 (ceiling) left in the goaf. The thickness of the ceiling in accordance with the requirements of the regulatory document should be at least 0.8 m. At the same time, in the mine field of the mine of the Third Mine Administration, there are areas with a ceiling thickness reduced to 0.66–0.70 m. The purpose of the author’s research was to determine the possibility of safe mining of the Third potash seam using the layered mining technology with a reduced thickness of the ceiling. In the course of a full-scale experiment, the geological structure and strength properties of the rocks of the ceiling, its stability in the bottomhole space and the intensity of loading of the bottomhole lining of the lower lavas have been studied in the paper. The research methods also included the analysis of literary sources and statistical processing of the obtained data. It has been established that a decrease in the thickness of the ceiling by 0.10–0.14 m from the required one does not have a significant effect on its strength, while it remains stable in the near-bottom space of the lower longwalls. The main indicators of the manifestation of rock pressure in the studied lower longwalls – the rate of increase of the bottomhole lining in the stope cycles and the lowering of the roof in the bottomhole space – did not exceed the similar indicators in the longwalls with the required thickness of the ceiling. The obtained data indicate the possibility of safemining of the Third potash seam using the layered excavation technology with the thickness of the interlayer rock salt pack 3–4 not less than 0.66 m. In this case, the bearing capacity of the bottomhole lining should be at least 550 kN/m2. ","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133036970","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 : 2022-12-09DOI: 10.21122/2227-1031-2022-21-6-511-516
V. N. Chernoivan, N. Chernoivan
Field studies of panel buildings have shown that after 30 years of operation, the technical condition of structural elements (embedded parts, welds, etc.) are in working condition. At the same time, the thermal characteristics of the external wall fencing have decreased by more than 30 % compared to those adopted during the design and do not meet regulatory requirements. One of the main reasons for this is the destruction of the material of the thermal insulation layer of wall panels under the influence of atmospheric influences. Consequently, the thermal rehabilitation of external wall panels allows for further operation of panel buildings without restrictions. According to the results of the studies carried out, it is proposed to use a factory-made thermal insulation cladding plate for thermal rehabilitation of the facades of operated panel buildings. The publication presents the results of laboratory studies on the choice of an effective solution for the design of the conection (joint) of individual thermal insulation plate into a thermal insulation facing plate of the required dimensions. The technology of manufacturing thermal insulation facing plates is described. The main advantages of the proposed structural and technological solution for the thermal rehabilitation of external wall panels are: a significant reduction in manual technological processes on the construction site; the possibility of performing work without eviction of residents; eliminating the appearance of cold bridges in the inter-panel seams during the operation of buildings through the use of a folding type joint.
{"title":"Thermal Rehabilitation of Facades of Operated Panel Buildings","authors":"V. N. Chernoivan, N. Chernoivan","doi":"10.21122/2227-1031-2022-21-6-511-516","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-6-511-516","url":null,"abstract":"Field studies of panel buildings have shown that after 30 years of operation, the technical condition of structural elements (embedded parts, welds, etc.) are in working condition. At the same time, the thermal characteristics of the external wall fencing have decreased by more than 30 % compared to those adopted during the design and do not meet regulatory requirements. One of the main reasons for this is the destruction of the material of the thermal insulation layer of wall panels under the influence of atmospheric influences. Consequently, the thermal rehabilitation of external wall panels allows for further operation of panel buildings without restrictions. According to the results of the studies carried out, it is proposed to use a factory-made thermal insulation cladding plate for thermal rehabilitation of the facades of operated panel buildings. The publication presents the results of laboratory studies on the choice of an effective solution for the design of the conection (joint) of individual thermal insulation plate into a thermal insulation facing plate of the required dimensions. The technology of manufacturing thermal insulation facing plates is described. The main advantages of the proposed structural and technological solution for the thermal rehabilitation of external wall panels are: a significant reduction in manual technological processes on the construction site; the possibility of performing work without eviction of residents; eliminating the appearance of cold bridges in the inter-panel seams during the operation of buildings through the use of a folding type joint.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130104446","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 : 2022-12-09DOI: 10.21122/2227-1031-2022-21-6-480-489
É. I. Mikhnevich, Ziming Li
Reservoirs with multifunctional purposes are the most widely used as sources of water for irrigation. In China, a large number of irrigation systems have been created using reservoirs as sources for flood prevention, irrigation, industrial and agricultural water supply. In Belarus, the Soligorsk, Lyuban, Petrovich, Pogost and other multifunctional reservoirs are used for irrigation. The useful (regulating) volume of a multifunctional reservoir consists of separate components calculated for each consumer in the basis of a hydrological and feasibility study. Thus, the useful volume of water intended for irrigation should provide the required irrigation capacity and capacity of the irrigation system. When determining the useful (regulating) volume of a multifunctional reservoir, the total water requirements for various purposes (water supply, irrigation, hydropower, etc.) are calculated. For each consumer, the required design supply is assigned and the appropriate method for determining water consumption is used. Reservoirs intended for water supply count on 95–97 % availability of runoff, and for irrigation purposes – on 75–80 % availability in zones of moderate and excessive moisture. In arid, desert and semi-desert regions of China, where lack of water in dry years can lead to large crop losses, irrigation reservoirs are expected to be 90–95 % secure. The volumes and costs of water in the reservoir for irrigation purposes must cover the needs of plants in water within the established time frame for the year of estimated availability. The paper provides a formula for determining the weighted average irrigation rate and the volume of water required for irrigation. A methodology is presented for calculating the useful volume of a reservoir intended for industrial water supply and irrigation, for which flow regulation is calculated for two supply of water consumption. A method is proposed for determining the flow rate of entrained sediments for various stages of their movement. A formula is presented for the total volume of suspended and bottom sediments entering the reservoir.
{"title":"Methodology for Calculating Water Supply for Irrigation from Reservoirs of Multifunctional Purpose (on the Example of China and Belarus","authors":"É. I. Mikhnevich, Ziming Li","doi":"10.21122/2227-1031-2022-21-6-480-489","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-6-480-489","url":null,"abstract":"Reservoirs with multifunctional purposes are the most widely used as sources of water for irrigation. In China, a large number of irrigation systems have been created using reservoirs as sources for flood prevention, irrigation, industrial and agricultural water supply. In Belarus, the Soligorsk, Lyuban, Petrovich, Pogost and other multifunctional reservoirs are used for irrigation. The useful (regulating) volume of a multifunctional reservoir consists of separate components calculated for each consumer in the basis of a hydrological and feasibility study. Thus, the useful volume of water intended for irrigation should provide the required irrigation capacity and capacity of the irrigation system. When determining the useful (regulating) volume of a multifunctional reservoir, the total water requirements for various purposes (water supply, irrigation, hydropower, etc.) are calculated. For each consumer, the required design supply is assigned and the appropriate method for determining water consumption is used. Reservoirs intended for water supply count on 95–97 % availability of runoff, and for irrigation purposes – on 75–80 % availability in zones of moderate and excessive moisture. In arid, desert and semi-desert regions of China, where lack of water in dry years can lead to large crop losses, irrigation reservoirs are expected to be 90–95 % secure. The volumes and costs of water in the reservoir for irrigation purposes must cover the needs of plants in water within the established time frame for the year of estimated availability. The paper provides a formula for determining the weighted average irrigation rate and the volume of water required for irrigation. A methodology is presented for calculating the useful volume of a reservoir intended for industrial water supply and irrigation, for which flow regulation is calculated for two supply of water consumption. A method is proposed for determining the flow rate of entrained sediments for various stages of their movement. A formula is presented for the total volume of suspended and bottom sediments entering the reservoir. ","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117296525","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 : 2022-12-09DOI: 10.21122/2227-1031-2022-21-6-517-524
D. Kapskiy, O. Larin, Thi Thu Hoai Nguyen, L. Khmelnitskaya
The paper presents the methodological provisions for the organization of logistics operations during the transportation of household electronic waste in large cities. Human activity is accompanied by the formation of waste, the amount of which has recently increased. In modern conditions, households actively use electronic and electrical devices. Therefore, a lot of household electronic and electrical waste is generated, which is hazardous to the environment and must be disposed of in accordance with legal requirements. The efficiency of disposal of household electronic waste depends on the organization of logistics operations for the collection, accumulation and removal of such waste. The main methodological stages of logistical support for the recycling process include the formation of a hierarchy of territorial formations (taxons), standardization of waste generation indicators for taxa of each level in the hierarchy, designing the configuration of a network of collection points for acceptance and temporary storage of waste within the boundaries of the service area, substantiating the rational storage capacity of each point and deadlines for waste storage; planning the transportation of waste from accumulation points to objects of their further processing. When planning the transportation of waste, the actual volume of waste accumulation at each collection point is taken into account, transportation routes are designed for the shortest distances, taking into account the capacity of vehicles. The main feature of the developed method of waste removal is the operational adjustment of routes so that the car drives only to those accumulation points where the actual volume of waste has reached the maximum storage capacity. This approach ensures timely waste collection and lower transportation costs compared to existing methods that organize waste collection at a specified frequency. The developed methodology was tested on the basis of statistical data from Hanoi (Vietnam). The results of numerical experiments show that the application of methods provides a reduction in transport costs for the removal of household electronic waste, and also increases the level of their collection and disposal.
{"title":"Organization of Logistics Operations for Transportation of Household Electronic Waste in Cities","authors":"D. Kapskiy, O. Larin, Thi Thu Hoai Nguyen, L. Khmelnitskaya","doi":"10.21122/2227-1031-2022-21-6-517-524","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-6-517-524","url":null,"abstract":"The paper presents the methodological provisions for the organization of logistics operations during the transportation of household electronic waste in large cities. Human activity is accompanied by the formation of waste, the amount of which has recently increased. In modern conditions, households actively use electronic and electrical devices. Therefore, a lot of household electronic and electrical waste is generated, which is hazardous to the environment and must be disposed of in accordance with legal requirements. The efficiency of disposal of household electronic waste depends on the organization of logistics operations for the collection, accumulation and removal of such waste. The main methodological stages of logistical support for the recycling process include the formation of a hierarchy of territorial formations (taxons), standardization of waste generation indicators for taxa of each level in the hierarchy, designing the configuration of a network of collection points for acceptance and temporary storage of waste within the boundaries of the service area, substantiating the rational storage capacity of each point and deadlines for waste storage; planning the transportation of waste from accumulation points to objects of their further processing. When planning the transportation of waste, the actual volume of waste accumulation at each collection point is taken into account, transportation routes are designed for the shortest distances, taking into account the capacity of vehicles. The main feature of the developed method of waste removal is the operational adjustment of routes so that the car drives only to those accumulation points where the actual volume of waste has reached the maximum storage capacity. This approach ensures timely waste collection and lower transportation costs compared to existing methods that organize waste collection at a specified frequency. The developed methodology was tested on the basis of statistical data from Hanoi (Vietnam). The results of numerical experiments show that the application of methods provides a reduction in transport costs for the removal of household electronic waste, and also increases the level of their collection and disposal.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123259627","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 : 2022-12-09DOI: 10.21122/2227-1031-2022-21-6-504-510
A. К. Кayumov, S. I. Zinevich, Y. V. Kovalev
Road bases are the main bearing layers of the road pavement, the purpose of which is the perception of the load from cars and its distribution on the subgrade soil. The base structure is determined by calculation depending on the planned traffic load and traffic intensity and usually consists of two layers, and for capital coatings, the upper layer of the two-layer base is made of materials reinforced with binders. The base of the pavement is a rather expensive construction and it is important for its construction, where possible, to use local materials, as well as secondary materials, i. e. industrial and construction industry waste. In the process of construction and repair works, the use of secondary raw materials can significantly reduce the cost of their implementation. Moreover, this practice not only reduces the cost of work, but also reduces the negative impact on the environment. The paper considers the possibility of constructing a pavement base from such secondary materials as spent molding sands (foundry waste), cement granulate (a product of crushing old cement concrete structures, construction waste) and asphalt granulate (a product of milling worn asphalt concrete pavements). In this case, the cost of the base is significantly reduced while еnsuring its necessary strength. Spent sands were used as a leveling layer, cement granulate
{"title":"Pavement Bases from Recycled Materials","authors":"A. К. Кayumov, S. I. Zinevich, Y. V. Kovalev","doi":"10.21122/2227-1031-2022-21-6-504-510","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-6-504-510","url":null,"abstract":"Road bases are the main bearing layers of the road pavement, the purpose of which is the perception of the load from cars and its distribution on the subgrade soil. The base structure is determined by calculation depending on the planned traffic load and traffic intensity and usually consists of two layers, and for capital coatings, the upper layer of the two-layer base is made of materials reinforced with binders. The base of the pavement is a rather expensive construction and it is important for its construction, where possible, to use local materials, as well as secondary materials, i. e. industrial and construction industry waste. In the process of construction and repair works, the use of secondary raw materials can significantly reduce the cost of their implementation. Moreover, this practice not only reduces the cost of work, but also reduces the negative impact on the environment. The paper considers the possibility of constructing a pavement base from such secondary materials as spent molding sands (foundry waste), cement granulate (a product of crushing old cement concrete structures, construction waste) and asphalt granulate (a product of milling worn asphalt concrete pavements). In this case, the cost of the base is significantly reduced while еnsuring its necessary strength. Spent sands were used as a leveling layer, cement granulate","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123169605","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 : 2022-12-02DOI: 10.21122/2227-1031-2022-21-6-464-472
V. A. Pumpur, A. Anisovich, K. E. Baranouski, P. Y. Duvalau, V. M. Andryienka
The features of the formation of castings from chromium cast iron during casting in a combined mold are studied using internal sources of heat removal introduced into the melt. A series of experiemеnts has been carried out with wear-resistant chromium cast iron. The following macrocoolers have been used: a 0.5 mm thick silumin plate containing 3–5 % Ti; a mixture of borax and crushed ferrochrome (1–4 mm); white cast iron shot. The phase composition of the samples has been determined by X-ray diffraction analysis, and their microstructure has been also studied. Hardness testing has been carried out on specimens obtained with cast iron shot. The most effective method of using an internal source of heat removal, which has a significant effect on the cooling rate of the casting and its microstructure, has been determined. The most promising was a mixture of borax and crushed ferrochrome particles, which did not dissolve in the melt and formed zones with local structure refinement, as well as white cast iron shot, a more technological alternative to ferrochrome. The use of white cast iron shot has led to a refinement of the structure of the part “Backing sheet У3.1,1 [U3.1.1]” made of wear-resistant chromium cast iron, as well as to an increase in the hardness of its working surface by 2.6 HRC. Almost all of the shot introduced into the melt has been melted. As a result of the research, it has been revealed that the use of ferrochrome and white cast iron shot is an effective way of local structure refinement and a practical possibility of obtaining a part made of chromium cast iron with increased hardness. All this can increase the wear resistance of parts of crushing and grinding equipment.
{"title":"On Application of Internal Heat Sink Sources when Producing Castings from Wear-Resistant Chromium Cast Iron","authors":"V. A. Pumpur, A. Anisovich, K. E. Baranouski, P. Y. Duvalau, V. M. Andryienka","doi":"10.21122/2227-1031-2022-21-6-464-472","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-6-464-472","url":null,"abstract":"The features of the formation of castings from chromium cast iron during casting in a combined mold are studied using internal sources of heat removal introduced into the melt. A series of experiemеnts has been carried out with wear-resistant chromium cast iron. The following macrocoolers have been used: a 0.5 mm thick silumin plate containing 3–5 % Ti; a mixture of borax and crushed ferrochrome (1–4 mm); white cast iron shot. The phase composition of the samples has been determined by X-ray diffraction analysis, and their microstructure has been also studied. Hardness testing has been carried out on specimens obtained with cast iron shot. The most effective method of using an internal source of heat removal, which has a significant effect on the cooling rate of the casting and its microstructure, has been determined. The most promising was a mixture of borax and crushed ferrochrome particles, which did not dissolve in the melt and formed zones with local structure refinement, as well as white cast iron shot, a more technological alternative to ferrochrome. The use of white cast iron shot has led to a refinement of the structure of the part “Backing sheet У3.1,1 [U3.1.1]” made of wear-resistant chromium cast iron, as well as to an increase in the hardness of its working surface by 2.6 HRC. Almost all of the shot introduced into the melt has been melted. As a result of the research, it has been revealed that the use of ferrochrome and white cast iron shot is an effective way of local structure refinement and a practical possibility of obtaining a part made of chromium cast iron with increased hardness. All this can increase the wear resistance of parts of crushing and grinding equipment.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121712723","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 : 2022-10-07DOI: 10.21122/2227-1031-2022-21-5-386-391
E. Y. Davydov
The calculation of building structures begins with the determination of loads and effects. The correctness of determining the values of loads and impacts, and in particular their calculated values, largely determines the reliability of structural forms, their durability and economic efficiency. The paper considers the regulatory documents for determining snow, wind and crane loads, as well as loads due to their own weight of load-bearing and enclosing structures. In most cases, changing the values of snow loads in the direction of their increase is labor- and material-intensive, since after this, it is required to examine all the supporting structures that perceive snow loads, recalculation them, and quite often, strengthen them. It is proposed to review snow loads no more than once every 20–25 years. Wind speed increases with height increases. This is confirmed by statistical data obtained at many weather stations located in the Republic of Belarus and foreign countries. Failure to take into account the change in wind pressure along the height leads to significant increase in the efforts from the wind load by 2-3 times. The increase in the efforts from the wind load, as well as from the snow load, entails the need for a mass survey of buildings and structures and, as a rule, expensive work to strengthen the supporting structures. Determination of loads from overhead cranes in the current regulatory documents is completely focused on the characteristics of European hoisting mechanisms, which largely does not correspond to the characteristics of cranes used in the Republic of Belarus. It is proposed to determine crane loads according to SP [Sanitary Regulations] CYbG20.133330.2011 “Loads and impacts” (updated edition of SNiP [Construction Standards and Regulations] 2.01.07–85*). When determining the design loads from the own mass of structural forms, the reliability factor for loads is used. The values of these coefficients in the current regulatory documents are unreasonably high, especially for metal structures.
{"title":"Analysis of Regulatory Documents for Determining Loads for Buildings and Structures","authors":"E. Y. Davydov","doi":"10.21122/2227-1031-2022-21-5-386-391","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-5-386-391","url":null,"abstract":"The calculation of building structures begins with the determination of loads and effects. The correctness of determining the values of loads and impacts, and in particular their calculated values, largely determines the reliability of structural forms, their durability and economic efficiency. The paper considers the regulatory documents for determining snow, wind and crane loads, as well as loads due to their own weight of load-bearing and enclosing structures. In most cases, changing the values of snow loads in the direction of their increase is labor- and material-intensive, since after this, it is required to examine all the supporting structures that perceive snow loads, recalculation them, and quite often, strengthen them. It is proposed to review snow loads no more than once every 20–25 years. Wind speed increases with height increases. This is confirmed by statistical data obtained at many weather stations located in the Republic of Belarus and foreign countries. Failure to take into account the change in wind pressure along the height leads to significant increase in the efforts from the wind load by 2-3 times. The increase in the efforts from the wind load, as well as from the snow load, entails the need for a mass survey of buildings and structures and, as a rule, expensive work to strengthen the supporting structures. Determination of loads from overhead cranes in the current regulatory documents is completely focused on the characteristics of European hoisting mechanisms, which largely does not correspond to the characteristics of cranes used in the Republic of Belarus. It is proposed to determine crane loads according to SP [Sanitary Regulations] CYbG20.133330.2011 “Loads and impacts” (updated edition of SNiP [Construction Standards and Regulations] 2.01.07–85*). When determining the design loads from the own mass of structural forms, the reliability factor for loads is used. The values of these coefficients in the current regulatory documents are unreasonably high, especially for metal structures.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126810135","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 : 2022-10-07DOI: 10.21122/2227-1031-2022-21-5-410-418
V. Sizov, A. Pavlovskaya
A comprehensive analysis of the multilayer wall panel has been performed. The heat-insulating layer, the thickness of which affects both the dimensions of the enclosing structure and the heat-shielding efficiency of the wall panel, has been studied,. Reducing the thickness of the thermal insulation layer is an important issue, since the production of three-layer panels is expensive in energy and material terms. The features of using a different number of screens to reduce the size of the thermal insulation layer are presented. An example of the possibility of a maximum reduction in the size of the heat-insulating layer, when the thickness of the interlayer din cannot be less than 3–5 mm is given. It is shown that the total thickness of the thermal insulation layer will be 0.057 m in the presence of the maximum possible number of screens – 12. For these conditions, the temperatures in the enclosure planes are calculated, according to the values of which the values of the maximum partial pressures E and partial pressures of water vapor e are determined (for the variants of perforated е¢ and non-perforated е¢¢ screens). According to the obtained values the dependences E, е¢, е¢¢ on the temperature in the planes of the fence are constructed. The calculations carried out and a general assessment of the heat and humidity regime in the enclosing structures were confirmed with the help of the compiled program and the calculation of the necessary parameters е and t in the layers of the structure. It has been established that various shielding materials can be used to exclude condensation zones during the operation of enclosing structures.
{"title":"Efficient Multi-Layer Wall Panel","authors":"V. Sizov, A. Pavlovskaya","doi":"10.21122/2227-1031-2022-21-5-410-418","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-5-410-418","url":null,"abstract":"A comprehensive analysis of the multilayer wall panel has been performed. The heat-insulating layer, the thickness of which affects both the dimensions of the enclosing structure and the heat-shielding efficiency of the wall panel, has been studied,. Reducing the thickness of the thermal insulation layer is an important issue, since the production of three-layer panels is expensive in energy and material terms. The features of using a different number of screens to reduce the size of the thermal insulation layer are presented. An example of the possibility of a maximum reduction in the size of the heat-insulating layer, when the thickness of the interlayer din cannot be less than 3–5 mm is given. It is shown that the total thickness of the thermal insulation layer will be 0.057 m in the presence of the maximum possible number of screens – 12. For these conditions, the temperatures in the enclosure planes are calculated, according to the values of which the values of the maximum partial pressures E and partial pressures of water vapor e are determined (for the variants of perforated е¢ and non-perforated е¢¢ screens). According to the obtained values the dependences E, е¢, е¢¢ on the temperature in the planes of the fence are constructed. The calculations carried out and a general assessment of the heat and humidity regime in the enclosing structures were confirmed with the help of the compiled program and the calculation of the necessary parameters е and t in the layers of the structure. It has been established that various shielding materials can be used to exclude condensation zones during the operation of enclosing structures.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116674807","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 : 2022-10-07DOI: 10.21122/2227-1031-2022-21-5-392-396
S. Leonovich, E. Sadovskaya
Concrete is the most commonly used building material worldwide. One of its main disadvantages is the fragility of fracture and low crack resistance. The use of dispersed reinforcement of concrete composites is a promising direction in solving this type of problem. Dispersed fibers, evenly distributed over the entire volume of the material, create a spatial frame and contribute to the inhibition of developing cracks under the action of destructive forces. In order to increase the fracture toughness of concrete, dispersed fiber reinforcement is increasingly used in practice. The beginning of crack nucleation occurs at the nanoscale in the cement matrix. Thus, the use of nano-reinforcement with dispersed nanofibers can have a positive effect on the crack resistance of the cement composite. It is proposed to consider carbon nanotubes as such nanofibers. The presence of carbon nanofibers changes the microstructure and nanostructure of cement modified with carbon nanotubes. The result of the processes occurring in capillaries and cracks are deformations in the intergranular matrix, the free flow of which is prevented by rigid clinker grains and nanocarbon tubes, which creates a certain stress intensity at the tips of the separation cracks. The working hypothesis is confirmed that the required fracture toughness of structural concrete is provided by multi-level reinforcement: at the level of the crystalline aggregate of cement stone – carbon nanotubes, and at the level of fine-grained concrete – various macro-sized fibers (steel, polymer). Reinforcement of a crystalline joint with carbon nanotubes leads to an increase in the fracture toughness of the matrix (cement stone) by 20 %, compressive strength by 12 %, and tensile strength in bending by 20 %. When reinforcing at the level of fine-grained concrete, we obtain a composite – nanofibre-reinforced concrete with fracture toughness.
{"title":"Nanofiber Concrete: Multi-Level Reinforcement","authors":"S. Leonovich, E. Sadovskaya","doi":"10.21122/2227-1031-2022-21-5-392-396","DOIUrl":"https://doi.org/10.21122/2227-1031-2022-21-5-392-396","url":null,"abstract":"Concrete is the most commonly used building material worldwide. One of its main disadvantages is the fragility of fracture and low crack resistance. The use of dispersed reinforcement of concrete composites is a promising direction in solving this type of problem. Dispersed fibers, evenly distributed over the entire volume of the material, create a spatial frame and contribute to the inhibition of developing cracks under the action of destructive forces. In order to increase the fracture toughness of concrete, dispersed fiber reinforcement is increasingly used in practice. The beginning of crack nucleation occurs at the nanoscale in the cement matrix. Thus, the use of nano-reinforcement with dispersed nanofibers can have a positive effect on the crack resistance of the cement composite. It is proposed to consider carbon nanotubes as such nanofibers. The presence of carbon nanofibers changes the microstructure and nanostructure of cement modified with carbon nanotubes. The result of the processes occurring in capillaries and cracks are deformations in the intergranular matrix, the free flow of which is prevented by rigid clinker grains and nanocarbon tubes, which creates a certain stress intensity at the tips of the separation cracks. The working hypothesis is confirmed that the required fracture toughness of structural concrete is provided by multi-level reinforcement: at the level of the crystalline aggregate of cement stone – carbon nanotubes, and at the level of fine-grained concrete – various macro-sized fibers (steel, polymer). Reinforcement of a crystalline joint with carbon nanotubes leads to an increase in the fracture toughness of the matrix (cement stone) by 20 %, compressive strength by 12 %, and tensile strength in bending by 20 %. When reinforcing at the level of fine-grained concrete, we obtain a composite – nanofibre-reinforced concrete with fracture toughness.","PeriodicalId":297325,"journal":{"name":"Science & Technique","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114598478","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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