Pub Date : 2021-04-09DOI: 10.32508/STDJET.V3ISI2.557
Thuần Văn Lưu, Hiền Hồ Thị Vũ, Vương Phạm Minh
Hệ thống mô phỏng điều khiển không lưu đã trở nên quen thuộc với các nước phát triển. Hơn nữa hiện tại ở Việt Nam, nhu cầu về hệ thống kiểm soát không lưu ngày càng lớn do sự bùng nổ của ngành hàng không dân dụng. Tuy nhiên chưa có một nghiên cứu hay một đơn vị nào xây dựng hệ thống này. Các Công ty quản lý bay miền Bắc và miền Nam đều mua các hệ thống mô phỏng kiểm soát tại sân với chi phí rất cao. Nhiều công ty quản lý bay khác cũng có nhu cầu cao về hệ thống này, kể cả các đơn vị quân đội. Nhu cầu này đã thúc đẩy nhóm nghiên cứu tìm kiếm giải pháp để xây dựng hệ thống mô phỏng kiểm soát không lưu phù hợp với nhu cầu đào tạo trong nước. Dựa trên các phần mềm mô phỏng mã nguồn mở riêng lẻ với một số tính năng cơ bản, nhóm nghiên cứu đã xây dựng thành công hệ thống mô phỏng kiểm soát không lưu tại sân kết hợp tái tạo khung cảnh 3D trực quan sinh động ứng dụng trong đào tạo huấn luyện kiểm soát viên không lưu.
{"title":"Xây dựng hệ thống mô phỏng kiểm soát không lưu tại sân phục vụ trong đào tạo huấn luyện","authors":"Thuần Văn Lưu, Hiền Hồ Thị Vũ, Vương Phạm Minh","doi":"10.32508/STDJET.V3ISI2.557","DOIUrl":"https://doi.org/10.32508/STDJET.V3ISI2.557","url":null,"abstract":"Hệ thống mô phỏng điều khiển không lưu đã trở nên quen thuộc với các nước phát triển. Hơn nữa hiện tại ở Việt Nam, nhu cầu về hệ thống kiểm soát không lưu ngày càng lớn do sự bùng nổ của ngành hàng không dân dụng. Tuy nhiên chưa có một nghiên cứu hay một đơn vị nào xây dựng hệ thống này. Các Công ty quản lý bay miền Bắc và miền Nam đều mua các hệ thống mô phỏng kiểm soát tại sân với chi phí rất cao. Nhiều công ty quản lý bay khác cũng có nhu cầu cao về hệ thống này, kể cả các đơn vị quân đội. Nhu cầu này đã thúc đẩy nhóm nghiên cứu tìm kiếm giải pháp để xây dựng hệ thống mô phỏng kiểm soát không lưu phù hợp với nhu cầu đào tạo trong nước. Dựa trên các phần mềm mô phỏng mã nguồn mở riêng lẻ với một số tính năng cơ bản, nhóm nghiên cứu đã xây dựng thành công hệ thống mô phỏng kiểm soát không lưu tại sân kết hợp tái tạo khung cảnh 3D trực quan sinh động ứng dụng trong đào tạo huấn luyện kiểm soát viên không lưu.","PeriodicalId":205539,"journal":{"name":"Science & Technology Development Journal - Engineering and Technology","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122564683","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 : 2021-03-14DOI: 10.32508/STDJET.V4I1.770
D. X. Bien, P. Hoang, LeDang Hung, D. M. Tung, Nguyen Tai-Hoai Thanh, N. H. Phong, Vuong Tien Trung, P. Tuan
The trend of scientific development in the future cannot fail to mention the great influence of the space field, but in the immediate future, the observational satellite systems are related to communication technology. In fact, in some countries with strong development of communication technology and space technology, the mechanical system of geostationary satellite monitoring antennas has certainly been thoroughly resolved. However, because of a specific technology, the sharing and transferring of design and manufacturing technology to developing countries is a great challenge. It is almost difficult to find published works related to mechanical design calculation and manufacture of geostationary satellite monitoring antenna systems. The problem of proactive grasping of technology, step by step autonomy in manufacturing technology of telecommunications equipment related to space technology has always been the goal of developing countries like Vietnam to limit technology dependence, minimizing technology transfer costs, ensuring national security. The first step in these problems is the autonomous construction of terrestrial transceivers such as geostationary satellite monitoring antennas. This paper presents the kinematics modeling analysis of the mechanical system of the geostationary satellite monitoring antenna. Each component of the antenna system is assumed a rigid body. The mathematical model is built based on multi-bodies kinematics and dynamics theory. The DENAVIT-HARTENBERG (D-H) homogeneous matrix method was used to construct the kinematics equations. The forward kinematics problem is analyzed to determine the position, velocity, acceleration, and workspace of the antenna system with given system motion limits. The inverse kinematics problem is mentioned to determine the kinematics behaviors of the antenna system with a given motion path in the workspace. The numerical simulation results kinematics were successfully applied in practice, especially for dynamics and control system analysis of geostationary satellite antenna systems.
{"title":"Kinematics modeling analysis of the geostationary satellite monitoring antenna system","authors":"D. X. Bien, P. Hoang, LeDang Hung, D. M. Tung, Nguyen Tai-Hoai Thanh, N. H. Phong, Vuong Tien Trung, P. Tuan","doi":"10.32508/STDJET.V4I1.770","DOIUrl":"https://doi.org/10.32508/STDJET.V4I1.770","url":null,"abstract":"The trend of scientific development in the future cannot fail to mention the great influence of the space field, but in the immediate future, the observational satellite systems are related to communication technology. In fact, in some countries with strong development of communication technology and space technology, the mechanical system of geostationary satellite monitoring antennas has certainly been thoroughly resolved. However, because of a specific technology, the sharing and transferring of design and manufacturing technology to developing countries is a great challenge. It is almost difficult to find published works related to mechanical design calculation and manufacture of geostationary satellite monitoring antenna systems. The problem of proactive grasping of technology, step by step autonomy in manufacturing technology of telecommunications equipment related to space technology has always been the goal of developing countries like Vietnam to limit technology dependence, minimizing technology transfer costs, ensuring national security. The first step in these problems is the autonomous construction of terrestrial transceivers such as geostationary satellite monitoring antennas. This paper presents the kinematics modeling analysis of the mechanical system of the geostationary satellite monitoring antenna. Each component of the antenna system is assumed a rigid body. The mathematical model is built based on multi-bodies kinematics and dynamics theory. The DENAVIT-HARTENBERG (D-H) homogeneous matrix method was used to construct the kinematics equations. The forward kinematics problem is analyzed to determine the position, velocity, acceleration, and workspace of the antenna system with given system motion limits. The inverse kinematics problem is mentioned to determine the kinematics behaviors of the antenna system with a given motion path in the workspace. The numerical simulation results kinematics were successfully applied in practice, especially for dynamics and control system analysis of geostationary satellite antenna systems.","PeriodicalId":205539,"journal":{"name":"Science & Technology Development Journal - Engineering and Technology","volume":"107 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128562273","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 : 2021-03-13DOI: 10.32508/STDJET.V4I1.782
L. H. Anh, Nguyễn Phụ Thượng Lưu, Nguyễn Thiên Phú, Trần Đình Nhật
The experimental method used in a frontal crash of cars costs much time and expense. Therefore, numerical simulation in crashworthiness is widely applied in the world. The completed car models contain a lot of parts which provided complicated structure, especially the rear of car models do not contribute to behavior of frontal crash which usually evaluates injuries of pedestrian or motorcyclist. In order to save time and resources, a simplification of the car models for research simulations is essential with the goal of reducing approximately 50% of car model elements and nodes. This study aims to construct the finite element models of front structures of vehicle based on the original finite element models. Those new car models must be maintained important values such as mass and center of gravity position. By using condition boundaries, inertia moment is kept unchanged on new model. The original car models, which are provided by the National Crash Analysis Center (NCAC), validated by using results from experimental crash tests. The modified (simplistic) vehicle FE models are validated by comparing simulation results with experimental data and simulation results of the original vehicle finite element models. LS-Dyna software provides convenient tools and very strong to modify finite element model. There are six car models reconstructed in this research, including 1 Pick-up, 2 SUV and 3 Sedan. Because car models were not the main object to evaluate in a crash, energy and behavior of frontal part have the most important role. As a result, six simplified car models gave reasonable outcomes and reduced significantly the number of nodes and elements. Therefore, the simulation time is also reduced a lot. Simplified car models can be applied to the upcoming frontal simulations.
{"title":"Reconstruction finite element model of cars","authors":"L. H. Anh, Nguyễn Phụ Thượng Lưu, Nguyễn Thiên Phú, Trần Đình Nhật","doi":"10.32508/STDJET.V4I1.782","DOIUrl":"https://doi.org/10.32508/STDJET.V4I1.782","url":null,"abstract":"The experimental method used in a frontal crash of cars costs much time and expense. Therefore, numerical simulation in crashworthiness is widely applied in the world. The completed car models contain a lot of parts which provided complicated structure, especially the rear of car models do not contribute to behavior of frontal crash which usually evaluates injuries of pedestrian or motorcyclist. In order to save time and resources, a simplification of the car models for research simulations is essential with the goal of reducing approximately 50% of car model elements and nodes. This study aims to construct the finite element models of front structures of vehicle based on the original finite element models. Those new car models must be maintained important values such as mass and center of gravity position. By using condition boundaries, inertia moment is kept unchanged on new model. The original car models, which are provided by the National Crash Analysis Center (NCAC), validated by using results from experimental crash tests. The modified (simplistic) vehicle FE models are validated by comparing simulation results with experimental data and simulation results of the original vehicle finite element models. LS-Dyna software provides convenient tools and very strong to modify finite element model. There are six car models reconstructed in this research, including 1 Pick-up, 2 SUV and 3 Sedan. Because car models were not the main object to evaluate in a crash, energy and behavior of frontal part have the most important role. As a result, six simplified car models gave reasonable outcomes and reduced significantly the number of nodes and elements. Therefore, the simulation time is also reduced a lot. Simplified car models can be applied to the upcoming frontal simulations.","PeriodicalId":205539,"journal":{"name":"Science & Technology Development Journal - Engineering and Technology","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126969706","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 : 2021-03-13DOI: 10.32508/STDJET.V4I1.788
H. Trinh, M. H. Bùi
Viscose as cellulosic origin, the cheapest of all cellulosic fabrics could be the best alternative. Viscose is manufactured from regenerated cellulose. In order to manufacture viscose, pulp of bamboo is treated with aqueous sodium hydroxide to form alkali cellulose. This alkali cellulose is then treated with carbon disulfide to form sodium cellulose xanthate. The xanthate is then dissolved in aqueous sodium hydroxide and allowed to depolymerize. After depolymerization, rayon fiber is produced from the ripened solution. Viscose is primarily employed in apparels, upholstery fabric, industrial clothing, and medical hygiene. Apparels, upholstery fabric, and industrial clothing segments account for key share of the viscose market. The medical hygiene segment is anticipated to expand during the forecast period. Demand for viscose fiber is anticipated to increase significantly in the near future due to the rise in global population, increase in standard of living, and growth in disposable income. Viscose is an eco-friendly product; thus, increase in awareness about eco-friendly products and decrease in production of cotton are estimated to augment the demand for viscose fiber. Viscose fabric exhibits some similar properties compared to cotton except its poor wet strength due to higher moisture regain. In this study, chemical finishes by different cross-linkers were applied to improve the wet strength of the viscose fabric. For this purpose, water repellent finishes were applied. Water repellent finish helped in reducing the molecular barrier around the individual fibres that lowered the surface tension of the fabric. It reduces the absorbency of viscose fabric hence leads to higher wet strength. Therefore, the treated viscose fabric exhibited better wet strength after applying water repellent finishes on it. Scanning electron microscope (SEM) was used to examine the surface of the fabric treated with chemicals. Tensile strength of viscose was increased 24.6%.
{"title":"The Improving properties of Viscose fabric by water repellent finish","authors":"H. Trinh, M. H. Bùi","doi":"10.32508/STDJET.V4I1.788","DOIUrl":"https://doi.org/10.32508/STDJET.V4I1.788","url":null,"abstract":"Viscose as cellulosic origin, the cheapest of all cellulosic fabrics could be the best alternative. Viscose is manufactured from regenerated cellulose. In order to manufacture viscose, pulp of bamboo is treated with aqueous sodium hydroxide to form alkali cellulose. This alkali cellulose is then treated with carbon disulfide to form sodium cellulose xanthate. The xanthate is then dissolved in aqueous sodium hydroxide and allowed to depolymerize. After depolymerization, rayon fiber is produced from the ripened solution. Viscose is primarily employed in apparels, upholstery fabric, industrial clothing, and medical hygiene. Apparels, upholstery fabric, and industrial clothing segments account for key share of the viscose market. The medical hygiene segment is anticipated to expand during the forecast period. Demand for viscose fiber is anticipated to increase significantly in the near future due to the rise in global population, increase in standard of living, and growth in disposable income. Viscose is an eco-friendly product; thus, increase in awareness about eco-friendly products and decrease in production of cotton are estimated to augment the demand for viscose fiber. Viscose fabric exhibits some similar properties compared to cotton except its poor wet strength due to higher moisture regain. In this study, chemical finishes by different cross-linkers were applied to improve the wet strength of the viscose fabric. For this purpose, water repellent finishes were applied. Water repellent finish helped in reducing the molecular barrier around the individual fibres that lowered the surface tension of the fabric. It reduces the absorbency of viscose fabric hence leads to higher wet strength. Therefore, the treated viscose fabric exhibited better wet strength after applying water repellent finishes on it. Scanning electron microscope (SEM) was used to examine the surface of the fabric treated with chemicals. Tensile strength of viscose was increased 24.6%.","PeriodicalId":205539,"journal":{"name":"Science & Technology Development Journal - Engineering and Technology","volume":"235 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114262463","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 : 2021-03-06DOI: 10.32508/STDJET.V4I1.792
Minh H. Nguyen, Nguyen Anh My, L. Q. Vĩnh, Vo Thanh Binh
Gear is one of the most common and important components in machinery. Evaluation on durability of gears plays crucial role in the assessment of the whole system reliability and service life. For other parts like shafts, the gears also act as loads. Therefore, dimensions and weight of the gears should be reduced as much as possible, contributing the size and weight reduction of the whole systems, which is essential to be cost-effectiveness. The current research focuses on optimal weight design problem of spur gears, such that the weight is minimized under the constraints taken from working conditions. The weight is a function of six variables, i.e. face width, shaft diameter of pinion, shaft diameter of gear, number of teeth on pinion, module and hardness. Constraints are derived based on AGMA standard and engineering handbooks, including the bending strength, the surface fatigue strength, the interference condition, the condition for uniform load distribution, the torsional strength of shaft on pinion and gear, and the center distance. The set of optimum design variables is determined by the heuristic algorithm Grey Wolf Optimizer (GWO). The accuracy and efficiency of the GWO in the optimal weight design problem of spur gears are assessed based on comparison with other popular methods, such as Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and Simulated Annealing (SA). It is noted that in previous works, some of the constraints are still violated. Therefore, a penalty term is taken into the objective function, such that any set of design variables that violates constraints will be considered as ``unfit'' by the algorithm. It is demonstrated that using the proposed approach by current work, the optimal weight and the corresponding set of design variable are very close to reference data. Yet the advantage of the proposed approach is exhibited in the fact that all of the constraints are satisfied.
{"title":"Optimal weight design problem of spur gears","authors":"Minh H. Nguyen, Nguyen Anh My, L. Q. Vĩnh, Vo Thanh Binh","doi":"10.32508/STDJET.V4I1.792","DOIUrl":"https://doi.org/10.32508/STDJET.V4I1.792","url":null,"abstract":"Gear is one of the most common and important components in machinery. Evaluation on durability of gears plays crucial role in the assessment of the whole system reliability and service life. For other parts like shafts, the gears also act as loads. Therefore, dimensions and weight of the gears should be reduced as much as possible, contributing the size and weight reduction of the whole systems, which is essential to be cost-effectiveness. The current research focuses on optimal weight design problem of spur gears, such that the weight is minimized under the constraints taken from working conditions. The weight is a function of six variables, i.e. face width, shaft diameter of pinion, shaft diameter of gear, number of teeth on pinion, module and hardness. Constraints are derived based on AGMA standard and engineering handbooks, including the bending strength, the surface fatigue strength, the interference condition, the condition for uniform load distribution, the torsional strength of shaft on pinion and gear, and the center distance. The set of optimum design variables is determined by the heuristic algorithm Grey Wolf Optimizer (GWO). The accuracy and efficiency of the GWO in the optimal weight design problem of spur gears are assessed based on comparison with other popular methods, such as Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and Simulated Annealing (SA). It is noted that in previous works, some of the constraints are still violated. Therefore, a penalty term is taken into the objective function, such that any set of design variables that violates constraints will be considered as ``unfit'' by the algorithm. It is demonstrated that using the proposed approach by current work, the optimal weight and the corresponding set of design variable are very close to reference data. Yet the advantage of the proposed approach is exhibited in the fact that all of the constraints are satisfied.","PeriodicalId":205539,"journal":{"name":"Science & Technology Development Journal - Engineering and Technology","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124279097","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 : 2021-01-15DOI: 10.32508/STDJET.V3I3.685
T. Ha, Xuan-Xinh Nguyen, Hoang Kha Ha
This paper studies a joint precoder and fronthaul compression design for full-duplex (FD) miltiple-input-multiple-output (MIMO) cloud radio access networks (CRANs). A cloud control unit (CU) communicates with multiple downlink and uplink users through FD radio units (RUs) connected to the CU through fronthaul links which are limited capacity. We address the energy efficiency (EE) maximization problem subject to the transmit power constraints at each RU, each user and the limited capacity of fronthaul links. Since the formulated design problem is a highly non-convex problem in design variables, we exploit a successive convex approximation (SCA) method to obtain the concave lower bound of the achievable sum rate and a convex upper bound of limited capacity fronthaul link functions. Then, we apply the Dinkelbach method to develop an efficient iterative algorithm guaranteeing convergence in which the convex optimization problems are solved. Numerical results are provided to investigate the EE of the proposed algorithm.
{"title":"Energy Efficiency Maximization for Full Duplex MIMO Cloud Radio Access Networks","authors":"T. Ha, Xuan-Xinh Nguyen, Hoang Kha Ha","doi":"10.32508/STDJET.V3I3.685","DOIUrl":"https://doi.org/10.32508/STDJET.V3I3.685","url":null,"abstract":"This paper studies a joint precoder and fronthaul compression design for full-duplex (FD) miltiple-input-multiple-output (MIMO) cloud radio access networks (CRANs). A cloud control unit (CU) communicates with multiple downlink and uplink users through FD radio units (RUs) connected to the CU through fronthaul links which are limited capacity. We address the energy efficiency (EE) maximization problem subject to the transmit power constraints at each RU, each user and the limited capacity of fronthaul links. Since the formulated design problem is a highly non-convex problem in design variables, we exploit a successive convex approximation (SCA) method to obtain the concave lower bound of the achievable sum rate and a convex upper bound of limited capacity fronthaul link functions. Then, we apply the Dinkelbach method to develop an efficient iterative algorithm guaranteeing convergence in which the convex optimization problems are solved. Numerical results are provided to investigate the EE of the proposed algorithm.","PeriodicalId":205539,"journal":{"name":"Science & Technology Development Journal - Engineering and Technology","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131642315","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 : 2020-12-27DOI: 10.32508/stdjet.v3isi3.635
Dang Van Vinh
Given a certain class K1 of algebraic structures. We study a problem of finding a class K2 of algebraic structures such that the class K1 is approximable into K2 with respect to various predicates by generalized characters from K1 to K2. The problem of minimization of approximation is also considered. Some theorems related to the problem of constructing an approximation class are obtained. The problem in question is much more complicated and actual than the approximation problem we have been studying before (see [2]-[6]). The results of the description of the approximation class play an important role in studying the solvability problem of the predicate P in the class of semigroups K. In particular, if the approximation class consists of finite semigroups, then this problem is solved positively. Even more difficult is the problem of determining the necessary conditions that class is an approximation class for a given class K.
{"title":"About the class of approximation by generalized characters","authors":"Dang Van Vinh","doi":"10.32508/stdjet.v3isi3.635","DOIUrl":"https://doi.org/10.32508/stdjet.v3isi3.635","url":null,"abstract":"Given a certain class K1 of algebraic structures. We study a problem of finding a class K2 of algebraic structures such that the class K1 is approximable into K2 with respect to various predicates by generalized characters from K1 to K2. The problem of minimization of approximation is also considered. Some theorems related to the problem of constructing an approximation class are obtained. The problem in question is much more complicated and actual than the approximation problem we have been studying before (see [2]-[6]). The results of the description of the approximation class play an important role in studying the solvability problem of the predicate P in the class of semigroups K. In particular, if the approximation class consists of finite semigroups, then this problem is solved positively. Even more difficult is the problem of determining the necessary conditions that class is an approximation class for a given class K. \u0000 ","PeriodicalId":205539,"journal":{"name":"Science & Technology Development Journal - Engineering and Technology","volume":"6 8","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120872296","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 : 2020-12-27DOI: 10.32508/stdjet.v3i4.744
N. T. Tran, T. Nguyễn, Trong Nguyen, Đình Anh Khôi Phạm
In transmission and distribution networks throughout the world and in Vietnam nowadays, power transformers that are operating in the networks often are in black-box condition, i.e. there is no internal information available in terms of geometrical structure and material parameters. Geometrical structure of power transformers includes mainly winding structure and additional parts such as a static end ring or a would-in shield coil, if any whereas main materials in power transformers consists of conductive, insulating and magnetic materials… This makes difficulties in faults diagnosis that is based on the approach of physical modeling in general and the so-called electrical equivalentcircuit based modeling in particular since the physical approach requires internal information of power transformers for calculating electrical parameters. In case the electrical equivalent-circuit approach is used, the diagnosis is then conducted based on the change of values of electrical parameters in the circuit before and after an alarm or a suspicious fault that happens when power transformers are in operation. Relevant international investigations conducted recently have mainly focused on test objects as power transformers in grey- or white-box condition, i.e. during manufacturing phase, since they have available geometrical structure and material properties. To show a possibility that blackbox power transformers could be investigated in a physical manner, this article introduces a new method in determining electrical parameters and geometrical structure applied on a black-box power transformer. The research is based on the Frequency Response Analysis technique and has developed recent relevant investigations of the authors. This enables investigations of the value change of electrical equivalent parameters of this transformer on its simulated frequency responses for the purpose of physical fault diagnosis of power transformers later on.
{"title":"A new method in determination of electrical parameters and geometrical structure of a power transformer applicable to failure diagnosis","authors":"N. T. Tran, T. Nguyễn, Trong Nguyen, Đình Anh Khôi Phạm","doi":"10.32508/stdjet.v3i4.744","DOIUrl":"https://doi.org/10.32508/stdjet.v3i4.744","url":null,"abstract":"In transmission and distribution networks throughout the world and in Vietnam nowadays, power transformers that are operating in the networks often are in black-box condition, i.e. there is no internal information available in terms of geometrical structure and material parameters. Geometrical structure of power transformers includes mainly winding structure and additional parts such as a static end ring or a would-in shield coil, if any whereas main materials in power transformers consists of conductive, insulating and magnetic materials… This makes difficulties in faults diagnosis that is based on the approach of physical modeling in general and the so-called electrical equivalentcircuit based modeling in particular since the physical approach requires internal information of power transformers for calculating electrical parameters. In case the electrical equivalent-circuit approach is used, the diagnosis is then conducted based on the change of values of electrical parameters in the circuit before and after an alarm or a suspicious fault that happens when power transformers are in operation. Relevant international investigations conducted recently have mainly focused on test objects as power transformers in grey- or white-box condition, i.e. during manufacturing phase, since they have available geometrical structure and material properties. To show a possibility that blackbox power transformers could be investigated in a physical manner, this article introduces a new method in determining electrical parameters and geometrical structure applied on a black-box power transformer. The research is based on the Frequency Response Analysis technique and has developed recent relevant investigations of the authors. This enables investigations of the value change of electrical equivalent parameters of this transformer on its simulated frequency responses for the purpose of physical fault diagnosis of power transformers later on.","PeriodicalId":205539,"journal":{"name":"Science & Technology Development Journal - Engineering and Technology","volume":"136 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122778775","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 : 2020-12-18DOI: 10.32508/stdjet.v3i3.659
Nho-Van Nguyen, H. Le
Multilevel voltage source inverters (VSIs) have been used for several decades thanks to their advantages compared with traditional two level VSI. Among various types of multilevel configuration, the T-type neutral-point-clamped VSI (3L TNPC VSI or 333-type VSI) has gained the attention in recent years. Due to the unique structure, the 333-type VSI has critical issues in reliability in operation such as switch-open-circuit (SOC) and switch-short-circuit (SSC), which lead to several unrequired issues, for instance, reduction of system performance, distorted and unbalanced output voltages and currents, or triggering the protection circuits. In some applications, the amplitude reduction and harmonics distortion of output voltages in SOC faults are not acceptable. Therefore, it is necessary to develop a pulse-width modulation (PWM) algorithm for 333-type VSI working under SOC fault which guarantees the desired output fundamental component voltage. The simultaneous SOC fault on two neutral-point-connected legs in the 333-type VSI may cause a large reduction in the output voltage. Under this circumstance, the 333-type VSI becomes an asymmetrical one called 322-type VSI. Certain studies regarding to the operation of 333-type VSI under SOC faults have been carried out. However, these studies require more semiconductor devices in order to create a redundant switching circuit. This leads to higher system cost with reduced inverter effieciency due to the additional loss. In this study, two carrier-based pulse-width modulation (CBPWM) techniques, i.e. 322-sinusoidal PWM (322-SPWM) and 322-medium offset CBPWM (322-MOCBPWM) are proposed for 322-type VSI. The proposed techniques are firstly simulated in MATLAB/Simulink and then implemented on a hardware setup. Performances of the proposed techniques are evaluated in terms of total harmonic distortion (THD) and weighted-THD (WTHD) of output voltages. Simulation results show that considering the worst output voltage under SOC fault, vBC, the proposed 322-SPWM technique could improve the THD by 40% and the WTHD by 94% compared with the uncompensated case with m=0.8. The corresponding results of 322-MOCBPWM technique are 42% and 96%, respectively. Characteristics of THD and WTHD values are also presented for demonstration the effectiveness of the proposed algorithm.
{"title":"A study on performances of carrier-based pulse-width modulation techniques for three-phase three-level t-type neutral-point-clamped inverter under switch-open-circuit fault on two neutral-point-connected legs","authors":"Nho-Van Nguyen, H. Le","doi":"10.32508/stdjet.v3i3.659","DOIUrl":"https://doi.org/10.32508/stdjet.v3i3.659","url":null,"abstract":"Multilevel voltage source inverters (VSIs) have been used for several decades thanks to their advantages compared with traditional two level VSI. Among various types of multilevel configuration, the T-type neutral-point-clamped VSI (3L TNPC VSI or 333-type VSI) has gained the attention in recent years. Due to the unique structure, the 333-type VSI has critical issues in reliability in operation such as switch-open-circuit (SOC) and switch-short-circuit (SSC), which lead to several unrequired issues, for instance, reduction of system performance, distorted and unbalanced output voltages and currents, or triggering the protection circuits. In some applications, the amplitude reduction and harmonics distortion of output voltages in SOC faults are not acceptable. Therefore, it is necessary to develop a pulse-width modulation (PWM) algorithm for 333-type VSI working under SOC fault which guarantees the desired output fundamental component voltage. The simultaneous SOC fault on two neutral-point-connected legs in the 333-type VSI may cause a large reduction in the output voltage. Under this circumstance, the 333-type VSI becomes an asymmetrical one called 322-type VSI. Certain studies regarding to the operation of 333-type VSI under SOC faults have been carried out. However, these studies require more semiconductor devices in order to create a redundant switching circuit. This leads to higher system cost with reduced inverter effieciency due to the additional loss. In this study, two carrier-based pulse-width modulation (CBPWM) techniques, i.e. 322-sinusoidal PWM (322-SPWM) and 322-medium offset CBPWM (322-MOCBPWM) are proposed for 322-type VSI. The proposed techniques are firstly simulated in MATLAB/Simulink and then implemented on a hardware setup. Performances of the proposed techniques are evaluated in terms of total harmonic distortion (THD) and weighted-THD (WTHD) of output voltages. Simulation results show that considering the worst output voltage under SOC fault, vBC, the proposed 322-SPWM technique could improve the THD by 40% and the WTHD by 94% compared with the uncompensated case with m=0.8. The corresponding results of 322-MOCBPWM technique are 42% and 96%, respectively. Characteristics of THD and WTHD values are also presented for demonstration the effectiveness of the proposed algorithm.","PeriodicalId":205539,"journal":{"name":"Science & Technology Development Journal - Engineering and Technology","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131175786","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 : 2020-12-18DOI: 10.32508/stdjet.v3i4.695
Khánh Hiếu Ngô, L. V. Le, H. Le
Centrifugal fan is a mechanical device working on the principle of centrifugal pump. When working, propeller sucks air along the axis, the pressure at the fan center will be small. The air will move from high pressure region to where the pressure is low. In other words, the air will receive additional centrifugal forces. The appearance of centrifugal fan has brought us many benefits such as basement ventilation systems or where ventilation fans enable to be directly established. Hence, the study of the performance characteristics of centrifugal fan is currently a matter concern, from which the improvement of performance can be applied to the fan. In this paper, a model simulating the performance characteristics of centrifugal fan was done on snappyHexMesh ultility with mainly hexahedron girds. Therefore, the results of the performance characteristics of centrifugal fan use k – omega SST is compared with experimental data. The results obtained from automatic meshing snappyHexmesh ultility and the SimpleFoam solver of open source OpenFOAM software provide the reliable data in the design and calculation of centrifugal fan. On this basis, the cost of improving the performance of centrifugal fan can be reduced considerably by numerical simulation.
{"title":"Numerical simulation of an industrial centrifugal fan 5,5 kW with OpenFOAM","authors":"Khánh Hiếu Ngô, L. V. Le, H. Le","doi":"10.32508/stdjet.v3i4.695","DOIUrl":"https://doi.org/10.32508/stdjet.v3i4.695","url":null,"abstract":"Centrifugal fan is a mechanical device working on the principle of centrifugal pump. When working, propeller sucks air along the axis, the pressure at the fan center will be small. The air will move from high pressure region to where the pressure is low. In other words, the air will receive additional centrifugal forces. The appearance of centrifugal fan has brought us many benefits such as basement ventilation systems or where ventilation fans enable to be directly established. Hence, the study of the performance characteristics of centrifugal fan is currently a matter concern, from which the improvement of performance can be applied to the fan. In this paper, a model simulating the performance characteristics of centrifugal fan was done on snappyHexMesh ultility with mainly hexahedron girds. Therefore, the results of the performance characteristics of centrifugal fan use k – omega SST is compared with experimental data. The results obtained from automatic meshing snappyHexmesh ultility and the SimpleFoam solver of open source OpenFOAM software provide the reliable data in the design and calculation of centrifugal fan. On this basis, the cost of improving the performance of centrifugal fan can be reduced considerably by numerical simulation.","PeriodicalId":205539,"journal":{"name":"Science & Technology Development Journal - Engineering and Technology","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132225562","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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