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Дисертації з теми "621.3.013.22"
Грецких, Светлана Владимировна. "Ослабление статического геомагнитного поля ферромагнитными элементами домов". Thesis, Государственное учреждение "Институт технических проблем магнетизма НАН Украины", 2015. http://repository.kpi.kharkov.ua/handle/KhPI-Press/21435.
Повний текст джерелаThesis for scientific degree of candidate of technical sciences, specialty 05.09.05 – theoretical electrical engineering. – National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2016. The thesis is devoted to mathematical modeling of the phenomenon of weakening of the static geomagnetic field (GMF) in residential homes and to the development of recommendations on how to normalize it to a safe level. The modeling of weakening of the GMF was performed with the help of the equivalent charges method. The cylindrical ferromagnetic column was taken as an example. In the framework of this technique the problem of calculation of the GMF’s induction weakened by extended ferromagnetic elements was solved. The physical parameters of the ferromagnetic column which effect the weakening of GMF are determined. The conditions under which GMF is reduced to the safety level are also determined. This is due to the changes of the GMF’s geometry and reducing of initial magnetic permeability of its material. The Arcadiev method of the effective magnetic permeability for modeling of magneticfield of reinforced concrete columns and intermediate floors was developed. The numerical modeling of static GMF in premises of houses with reinforced concrete structures was performed. The numerical results were experimentally confirmed. The recommendations for normalizing of GMF for creating safe and comfortable living conditions are given. These recommendations should be taken into account in designing modern premises of houses.
Грецьких, Світлана Володимирівна. "Ослаблення статичного геомагнітного поля феромагнітними елементами будинків". Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/21433.
Повний текст джерелаThesis for scientific degree of candidate of technical sciences, specialty 05.09.05 – theoretical electrical engineering. – National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2016. The thesis is devoted to mathematical modeling of the phenomenon of weakening of the static geomagnetic field (GMF) in residential homes and to the development of recommendations on how to normalize it to a safe level. The modeling of weakening of the GMF was performed with the help of the equivalent charges method. The cylindrical ferromagnetic column was taken as an example. In the framework of this technique the problem of calculation of the GMF’s induction weakened by extended ferromagnetic elements was solved. The physical parameters of the ferromagnetic column which effect the weakening of GMF are determined. The conditions under which GMF is reduced to the safety level are also determined. This is due to the changes of the GMF’s geometry and reducing of initial magnetic permeability of its material. The Arcadiev method of the effective magnetic permeability for modeling of magneticfield of reinforced concrete columns and intermediate floors was developed. The numerical modeling of static GMF in premises of houses with reinforced concrete structures was performed. The numerical results were experimentally confirmed. The recommendations for normalizing of GMF for creating safe and comfortable living conditions are given. These recommendations should be taken into account in designing modern premises of houses.
Ткаченко, Олександр Олегович. "Магнітне поле високовольтних кабельних ліній при двосторонньому заземленні екранів кабелів". Thesis, Інститут технічних проблем магнетизму Національної академії наук України, 2018. http://repository.kpi.kharkov.ua/handle/KhPI-Press/40754.
Повний текст джерелаThesis for scientific degree of candidate of technical sciences (Ph.D.), specialty 05.09.05 – theoretical electrical engineering. – National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2019. The thesis is devoted to the advancement of methods of physico-mathematical simulation and calculation of the magnetic field created by the high-voltage three-phase cable lines consisting of single-core cables with two-point bonded cable shields. The current tendency of the development of city electric networks implies an increasingly widespread use of three-phase high-voltage cable lines performed by ingleconductor cables with cross-linked polyethylene insulation. However, the cable line magnetic field can exceed the reference level for the population (0.5 μT for living space and 10 μT for an urban area). Therefore, when designing cable lines it is mandatory to calculate accurately their magnetic field using existing regulation documents and analytical solutions based on known methods. At the same time, in the case of two-point bonding, the cable shields form closed loops in which longitudinal currents are induced. These currents create an additional magnetic field that substantially changes the initial cable line magnetic field, that must be taken into account. The problem of simulation of the magnetic field of the cable line with two-point bonded cable shields can be solved numerically. However, analytical methods are more affordable for cable line designers. Also, these methods produce results with a transparent physical interpretation. However, the analytical methods of solving these problems are insufficiently studied. This is due to the lack of theoretically based methods for determining the complex amplitude of currents in the shields of three-phase cable lines and the methods of magnetic field simulating at any arrangement of phase cables. In the thesis, the features of a three-phase cable line with two-point bonded shields as the source of the magnetic field are investigated. It is shown that correct methods of calculating the magnetic field of cable lines can be created only if the currents in cable shields, which are inductively connected with the currents in cable cores, are determined. The analysis of electromagnetic processes in a three-phase cable line with two-point bonded shields based on the method of complex amplitudes is carried out. A generalized physico-mathematical model of the magnetic field of cable lines is developed. It allows to calculate the electric currents induced in shields of cables and to determine the magnetic field distribution for the arbitrary arrangement of cables. The exact expression for the magnetic field shielding factor for the trefoil cable line with two-point bonded shields is obtained. Using the Clark transformation, a simplistic expression for the magnetic field shielding factor is received for the flat cable line with twopoint bonded shields. Its error is within 5%. The possibility of the magnetic field shielding factor 2-4 times increase by ferromagnetic cores installed on cables is justified theoretically and experimentally. In this case the shielding factor depends on parameters of ferromagnetic cores, parameters of cables and their arrangement. The respective expressions for the shielding factor are obtained for trefoil and flat cable lines. The verification of the proposed physico-mathematical model and analytical expressions is performed by numerical simulation and experimentally. Methodologies of the magnetic field and root-mean-square shield currents calculating for the cable line with two-point bonded cable shields are developed.
Ткаченко, Олександр Олегович. "Магнітне поле високовольтних кабельних ліній при двосторонньому заземленні екранів кабелів". Thesis, Національний технічний університет "Харківський політехнічний інститут", 2019. http://repository.kpi.kharkov.ua/handle/KhPI-Press/40753.
Повний текст джерелаThesis for scientific degree of candidate of technical sciences (Ph.D.), specialty 05.09.05 – theoretical electrical engineering. – National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2019. The thesis is devoted to the advancement of methods of physico-mathematical simulation and calculation of the magnetic field created by the high-voltage three-phase cable lines consisting of single-core cables with two-point bonded cable shields. The current tendency of the development of city electric networks implies an increasingly widespread use of three-phase high-voltage cable lines performed by ingleconductor cables with cross-linked polyethylene insulation. However, the cable line magnetic field can exceed the reference level for the population (0.5 μT for living space and 10 μT for an urban area). Therefore, when designing cable lines it is mandatory to calculate accurately their magnetic field using existing regulation documents and analytical solutions based on known methods. At the same time, in the case of two-point bonding, the cable shields form closed loops in which longitudinal currents are induced. These currents create an additional magnetic field that substantially changes the initial cable line magnetic field, that must be taken into account. The problem of simulation of the magnetic field of the cable line with two-point bonded cable shields can be solved numerically. However, analytical methods are more affordable for cable line designers. Also, these methods produce results with a transparent physical interpretation. However, the analytical methods of solving these problems are insufficiently studied. This is due to the lack of theoretically based methods for determining the complex amplitude of currents in the shields of three-phase cable lines and the methods of magnetic field simulating at any arrangement of phase cables. In the thesis, the features of a three-phase cable line with two-point bonded shields as the source of the magnetic field are investigated. It is shown that correct methods of calculating the magnetic field of cable lines can be created only if the currents in cable shields, which are inductively connected with the currents in cable cores, are determined. The analysis of electromagnetic processes in a three-phase cable line with two-point bonded shields based on the method of complex amplitudes is carried out. A generalized physico-mathematical model of the magnetic field of cable lines is developed. It allows to calculate the electric currents induced in shields of cables and to determine the magnetic field distribution for the arbitrary arrangement of cables. The exact expression for the magnetic field shielding factor for the trefoil cable line with two-point bonded shields is obtained. Using the Clark transformation, a simplistic expression for the magnetic field shielding factor is received for the flat cable line with twopoint bonded shields. Its error is within 5%. The possibility of the magnetic field shielding factor 2-4 times increase by ferromagnetic cores installed on cables is justified theoretically and experimentally. In this case the shielding factor depends on parameters of ferromagnetic cores, parameters of cables and their arrangement. The respective expressions for the shielding factor are obtained for trefoil and flat cable lines. The verification of the proposed physico-mathematical model and analytical expressions is performed by numerical simulation and experimentally. Methodologies of the magnetic field and root-mean-square shield currents calculating for the cable line with two-point bonded cable shields are developed.
Чуніхін, Костянтин Вадимович. "Магнітне поле електромагнітів систем керування космічними апаратами". Thesis, Національний технічний університет "Харківський політехнічний інститут", 2019. http://repository.kpi.kharkov.ua/handle/KhPI-Press/42298.
Повний текст джерелаThesis for scientific degree of candidate of technical sciences in specialty 05.09.05 – theoretical electrical engineering. – National Technical University «Kharkiv Polytechnic Institute», Kharkiv, 2019. The thesis is devoted to the improvement of the mathematical model of magnetic field of DC electromagnets of spacecraft control systems considering the heterogeneity of the magnetization of the cores of cylindrical and complex shape. The integral equation with respect to the surface density of fictitious magnetic charges was transformed on the basis of almost uniform distribution of magnetization in the cross sections of the core and by means of the averages of the volume of each element of the core of magnetic permeabilities, which allows to calculate the magnetic field of electromagnets of spacecraft control systems taking into account the edge effects and the magnetization curve. The influence of the magnetic field intensity generated by the coil, the relative length of the cores of cylindrical and complex shape made of permalloy 50N, as well as the sizes and positions of the pole pieces on the magnetic moment of the electromagnet is studied and recommendations are made to ensure its maximum effective specific magnetic moment. The validity of the theoretical results is confirmed by measuring the mean values of the magnetic field induction in the cross sections of a cylindrical core, comparing it with the published calculated values of the magnetic moment of cylindrical cores, and testing the mathematical model using analytical solutions of similar electrostatic problems.
Чуніхін, Костянтин Вадимович. "Магнітне поле електромагнітів систем керування космічними апаратами". Thesis, Національний технічний університет "Харківський політехнічний інститут", 2019. http://repository.kpi.kharkov.ua/handle/KhPI-Press/42300.
Повний текст джерелаThesis for the scientific degree of candidate of technical sciences (Ph.D.) in specialty 05.09.05 «Theoretical electrical engineering». – State Institution «Institute of Technical Problems of Magnetism of the National Academy of Sciences of Ukraine», National Technical University «Kharkiv Polytechnic Institute», Kharkiv, 2019. The thesis is devoted to the improvement of the mathematical model of magnetic field of DC electromagnets of spacecraft control systems considering the heterogeneity of the magnetization of the cores of cylindrical and complex shape. Due to scarcity of resources, while in the Earth's space, they are increasingly switching to passive spacecraft control systems, including magnetic control systems. The advantage of passive over active control systems is the lack of working body, which is a key factor in the long-term location of the spacecraft in the Earth's space. In the case of the use of magnetic control systems, which also include magnetic executive bodies, the problem arises to achieve the required control torque while limiting the dimensions of the spacecraft. Since the control moment of the spacecraft's control point is the magnetic moment, the need to reach its specified level while reducing mass, energy, and dimensions is one of the main tasks in the design of magnetic executive bodies. One of the types of magnetic executive bodies is the DC electromagnets. In the most common case, they consist of a cylindrical core of high magnetic permeability material and coaxial magnetizing coil. To increase the magnetic moment of the electromagnet pole pieces are used, which are located near the ends of the cylindrical core. The calculation of the magnetic moment of the electromagnet is quite complex scientific problems. This is due to the need to consider the nonlinear properties of the core material when determining its magnetic moment as the main part of the magnetic moment of the electromagnet. A critical analysis of the known methods of calculating the magnetic field and the magnetic moment of the cores of electromagnets is carried out. It is established that the methods based on the application of demagnetizing factors and integral equations do not consider the heterogeneity and nonlinearity of the magnetization of the cores of cylindrical and complex shape, as well as the inhomogeneity of the magnetic field generated by the coil. It is shown that the use of electrostatic analogy for the calculation of the magnetostatic field in inhomogeneous magnetizing media is correct on the basis of the dipole magnetization model, but in the formulas of the potential field, the correct use of magnetization by molecular currents is possible. The integral equation with respect to the surface density of fictitious magnetic charges was transformed on the basis of almost uniform distribution of magnetization in the cross sections of the core and by means of the averages of the volume of each element of the core of magnetic permeabilities, which allows to calculate the magnetic field of electromagnets of spacecraft control systems taking into account the edge effects and the magnetization curve. The influence of the magnetic field intensity generated by the coil, the relative length of the cores of cylindrical and complex shape made of permalloy 50N, as well as the sizes and positions of the pole pieces on the magnetic moment of the electromagnet is studied and found that cylindrical cores having a relative length b/R=16, 33, 66 at the level of the magnetic field, generated by the coil,H0=1647÷9888 A/m is provide the magnetic moment ranges of the electromagnets Mem=0,4÷2,3; 2,2÷12,2; 12,3÷28,8 A·m2 and the pole pieces of the cylindrical cores increase the magnetic moment of the electromagnet depending on their size and distance from the ends at b/R=16 to 50 %, at b/R=33 to 32 % and at b/R=66 to 11 %. Based on these studies, the following recommendations have been developed to ensure the maximum effective specific magnetic moment of the electromagnet. The coil of the electromagnet with the cores of cylindrical and complex shape should provide such levels of an external magnetic field at which the resultant magnetic field strength on the vast majority of the core is outside the saturation zone of the magnetization curve and corresponds to greater magnetization. Under these conditions, the growth of Mem can be achieved by increasing the b/R, the outer radius Rw, and the thickness hw of the pole pieces. The use of cylindrical cores made of permalloy 50N at b/R=16 is inefficient, and the pole pieces increase the efficiency of cores with b/R=16 at H0=6587 A/m. To ensure the maximum effective specific magnetic moment of electromagnets with cores of cylindrical and complex shape made of permalloy 50N with b/R=33 the magnetic field level of the coil H0=6587 A/m is recommended, and for cores with b/R=66 the magnetic field H0=3293 A/m is recommended. The pole pieces must be at the ends of the core and have the following dimensions: for b/R=16 and 33 is Rw=11 mm, hw=1÷4 mm and hw=6÷12 mm, for b/R=66 is Rw=8 mm, hw=8÷32 mm. The validity of the theoretical results is confirmed by measuring the mean values of the magnetic field induction in the cross sections of a cylindrical core, comparing it with the published calculated values of the magnetic moment of cylindrical cores, and testing the mathematical model using analytical solutions of similar electrostatic problems. In the work the author obtained the following new scientific results. The use of electrostatic analogy was further developed, which made it possible to formulate an integral equation with respect to the surface density of fictitious magnetic charges to calculate a plane-meridian magnetostatic field in a piecewise homogeneous magnetized medium and to test its numerical solution. For the first time, on the basis of a virtually uniform distribution of magnetization in the cross sections of the core, the original integral equation was transformed to calculate the magnetic field of electromagnets, which allowed to reduce the order of the approximating system of algebraic equations by 10÷12 times. For the first time, to calculate the nonlinear properties of the core material in the numerical solution of the integral equation, the average volume of the core elements of the magnetic permeability was used to calculate the magnetic field of the electromagnets, which reduced the size of the area of the integral equation solution by 6÷9 times. The results obtained by the author are of considerable practical importance. The mathematical model of the magnetic field of the electromagnets of the spacecraft control systems, as well as the recommendations regarding the shape, dimensions of the cores, the level of the magnetic field created by the coil, can be applied in the design of electromagnets that provide a given magnetic moment. The main results of the thesis have been used in the State Institution “Institute of Technical Problems of Magnetism of the National Academy of Sciences of Ukraine” when conducting research on budget topics.