Relevant bibliographies by topics / Magnetic shields

Academic literature on the topic 'Magnetic shields'

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Published: 14 March 2023

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Journal articles on the topic "Magnetic shields"

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Rayne, R. J., L. E. Toth, B. A. Bender, S. H. Lawrence, M. M. Miller, R. J. Soulen, and G. Candella. "Casting and machining of devices of high temperature superconducting BSCCO." Journal of Materials Research 6, no. 3 (March 1991): 467–72. http://dx.doi.org/10.1557/jmr.1991.0467.

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Magnetic shields for SQUID applications were successfully fabricated using high Tc superconducting Bi–Sr–Ca–Cu–O (BSCCO). In order to produce shields with adequate superconducting properties and close dimensional control, it was necessary to develop several new processing techniques. Shields were produced by casting liquid BSCCO into molds, heat treating, and machining. A series of BSCCO alloys with different compositions were cast from the molten state into metal molds and subsequently heat treated to render the castings superconducting. The heat-treating cycles were studied with the aid of thermogravimetric analysis (TGA), differential thermal analysis (DTA), and dilatometer measurements. The phases and microstructures after various heat-treating cycles were monitored by x-ray diffraction (XRD), optical microscopy, and scanning electron microscopy (SEM). Superconducting properties were measured after various stages of heat treatment and machining. Prototype magnetic shields were machined from bulk castings and found to perform successfully. The most significant factor in shield quality was the nominal composition of the shield, which was shown by transmission electron microscopy (TEM) to affect the grain boundary chemistry.
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Bondarenko, Alexey, Nikolay Vinokurov, and Sergey Miginky. "Beam Extraction From a Synchrotron Through a Magnetic Shield: Magnetic Measurements and Simulation of Efficiency." Siberian Journal of Physics 4, no. 2 (July 1, 2009): 40–46. http://dx.doi.org/10.54362/1818-7919-2009-4-2-40-46.

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A new beam extraction scheme from a synchrotron is put forward. The main difference from other extraction schemes is the use of magnetic shields instead of a septum. The magnetic shield is a multi-layer copper-iron tube, which are located in the central dipole magnets of a pulsed chicane. Numerical simulations and experimental results for the field perturbation by magnetic shield are presented and compared. The calculation of extraction efficiency is presented.
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Solobai, A. A., A. V. Trukhanov, and S. S. Grabchikov. "Ni-Fe Alloys as Perspective Materials for Highly Efficient Magnetostatic Shielding." Solid State Phenomena 284 (October 2018): 375–79. http://dx.doi.org/10.4028/www.scientific.net/ssp.284.375.

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Magnetostatic shields based on Ni-Fe alloys were obtained via electrochemistry method with different thickness of partial magnetic layers. The experimental researches of the magnetic properties and magnetostatic shielding effectiveness of the single-layer and malty-layer cylindrical sample of the shields based on the electrodeposited Ni80Fe20 and Ni50Fe50 alloy are carried out. It has been shown that shields of gradient type (200 μm Ni50Fe50+200 μm Ni80Fe20 and 100 μm Ni50Fe50+300 μm Ni80Fe20) containing layers with different values of saturation induction (Bs) have a higher shielding efficiency than shield of a symmetric type (400 μm Ni50Fe50 and 400 μm Ni80Fe20). Maximum efficiency of magnetostatic shielding has been noted for 200 μm Ni50Fe50+ 200 μm Ni80Fe20 sample. It opens wide prospects for practical application for protection of the microelectronics devices against permanent magnetic fields.
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Sergeant, Peter, Ivan Cimrák, Valdemar Melicher, Luc Dupré, and Roger Van Keer. "Adjoint Variable Method for the Study of Combined Active and Passive Magnetic Shielding." Mathematical Problems in Engineering 2008 (2008): 1–15. http://dx.doi.org/10.1155/2008/369125.

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For shielding applications that cannot sufficiently be shielded by only a passive shield, it is useful to combine a passive and an active shield. Indeed, the latter does the “finetuning” of the field reduction that is mainly caused by the passive shield. The design requires the optimization of the geometry of the passive shield, the position of all coils of the active shield, and the real and imaginary components of the currents (when working in the frequency domain). As there are many variables, the computational effort for the optimization becomes huge. An optimization using genetic algorithms is compared with a classical gradient optimization and with a design sensitivity approach that uses an adjoint system. Several types of active and/or passive shields with constraints are designed. For each type, the optimization was carried out by all three techniques in order to compare them concerning CPU time and accuracy.
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Duc, H. B., T. P. Minh, D. B. Minh, N. P. Hoai, and V. D. Quoc. "An Investigation of Magnetic Field Influence in Underground High Voltage Cable Shields." Engineering, Technology & Applied Science Research 12, no. 4 (August 7, 2022): 8831–36. http://dx.doi.org/10.48084/etasr.5021.

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Magnetic fields and the shielding efficiency of the shields of underground high voltage cables are studied in this paper regarding several shielding configurations and materials. Shielding efficiency and magnetic fields are computed for shields with the same mesh but from different shielding materials, such as aluminum, ferrite, metal, and steel. In order to get the best shield configuration depending on the source characteristics and the material, a conducting ferromagnetic region with various thickness values is considered as shielding. A finite element model is introduced to investigate the influence of the parameters of magnetic fields and the shielding efficiency of underground high voltage cables. Furthermore, the reduction of the magnetic fields with or without shieldings is also presented. The developed method is performed with the magnetic vector potential formulations and validated on a practical problem.
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Wu, G. H., Xiao Li Huang, Mao Qiang Duan, Qiang Zhang, and X. Chen. "Studies on Magnetic Shielding Effectiveness by Finite Element Method." Advanced Materials Research 79-82 (August 2009): 1233–36. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.1233.

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Maxwell 2D software is introduced in this paper to calculate the magnetic shielding effectiveness (MSE) properties of iron plate. The three-dimensional magnetic shield is thought isotropic and simplified as two-dimensional model to study its MSE properties by the finite element method. In this method, a uniform magnetic field is generated by two huge magnets and the MSE properties of iron plate, which is in the centre of the uniform magnetic field, is then calculated by the ratio of magnetic field intensity after and before magnetic shielding. All the results indicate that shape of shield materials affects the MSE properties much and the MSE properties of shield with square and circular shape with 3mm in depth are 39.3 and 53.5 dB, respectively. That means the shield shape with fewer bending is favorable to the conductivity of magnetic energy. It also shows that the MSE value decreased linearly with the distance between the magnetic shield and the centre of the magnetic field. That is, the increase of side length of magnetic shield will lead to the decrease of MSE properties of iron plate, which is agreement with the theoretical prediction of Lu H.M. model. Furthermore, the MSE properties of double layers shielding (iron plate with 2mm in depth and 3mm iron plate with 81% porosity) are also studied in this paper. The effect of places of iron plate with 2mm in depth is presented to play important role in double layers shielding and the MSE value increases with the distance between the two magnetic shields. Compared to that of shield with circular shape, the MSE properties are similar to each other when the distance of the two shields is 8mm. In addition, it also indicates that the MSE value is higher when the iron plate with 2mm in depth is inside of the other than that when it is outside.
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Zhao, Yiyang, Zhiyin Sun, Donghua Pan, Shengxin Lin, Yinxi Jin, and Liyi Li. "A New Approach to Calculate the Shielding Factor of Magnetic Shields Comprising Nonlinear Ferromagnetic Materials under Arbitrary Disturbances." Energies 12, no. 11 (May 29, 2019): 2048. http://dx.doi.org/10.3390/en12112048.

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To enable the realization of ultra-low magnetic fields for scientific and technological research, magnetic shielding is required to create a space with low residual magnetic field and high shielding factors. The shielding factors of magnetic shields are due to nonlinear material properties, the geometry and structure of the shields, and the external magnetic fields. Magnetic shielding is used in environments full of random realistic disturbances, resulting in an arbitrary and random external magnetic field, and in this case, the shielding effect is hard to define simply by the shielding factors. A new method to simulate and predict a dynamic internal space magnetic field wave is proposed based on the Finite Element method (FEM) combined with the Jiles-Atherton (JA) model. By simulating the hysteresis behavior of the magnetic shields and establishing a dynamic model, the new method can simulate dynamic magnetic field changes inside magnetic shields as long as the external disturbances are known. The shielding factors under an AC external field with a sine wave and certain frequencies are calculated to validate the feasibility of the new method. A real-time wave of internal magnetic flux density under an AC triangular wave external field is simulated directly with the new method versus a method that splits the triangular wave into several sine waves by a Fourier transform, divides the shielding factors, and then adds the quotients together. Moreover, real-time internal waves under some arbitrary fields are measured. Experimental internal magnetic flux density waves of a 4-layer magnetically shielded room (MSR) at the Harbin Institute of Technology (HIT) fit the simulated results well, taking experimental errors into account.
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Witczak, Pawel Zygmunt, and Michal Swiatkowski. "Magnetic forces applied to the tank walls of a large power transformer." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 35, no. 6 (November 7, 2016): 2087–94. http://dx.doi.org/10.1108/compel-03-2016-0094.

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Purpose The purpose of this paper is to calculate forces created by the magnetic leakage field, which are directly applied to tank walls via magnetic shield. Design/methodology/approach Electromagnetic and mechanical calculations use 3D finite element technology, both applied to materials having constant orthotropic properties. The magnetic solver uses harmonic excitation; the analysis of mechanical deflection is carried out in static conditions. Two types of forces are considered: magnetostatic surface forces and magnetostriction volumetric ones. In measurements, the laser scanning vibrometer was applied. Findings Electromagnetic calculations must use an FE mesh much denser than that for typical power loss analysis. The magnetic orthotropy of the shield material does not create any important effects and it may be omitted. Magnetostriction forces are similar in value to magnetostatic ones, but their influence on the shield deformation is negligible. Research limitations/implications The results obtained for the analysis of the displacement of elements of the tank wall are exemplary – they show the difference between magnetostatic and magnetostriction excitation only. The analysis of the vibration of the transformer tank must include the presence of the oil inside the tank. Originality/value The asymmetrical placement of magnetic shields against the transformer core creates the visible differences in the magnitudes of magnetostatic forces applied to particular shields. Therefore, the design of magnetic shielding should also include the vibrational point of view.
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Packer, M., P. J. Hobson, A. Davis, N. Holmes, J. Leggett, P. Glover, N. L. Hardwicke, M. J. Brookes, R. Bowtell, and T. M. Fromhold. "Magnetic field design in a cylindrical high-permeability shield: The combination of simple building blocks and a genetic algorithm." Journal of Applied Physics 131, no. 9 (March 7, 2022): 093902. http://dx.doi.org/10.1063/5.0071986.

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Magnetically sensitive experiments and newly developed quantum technologies with integrated high-permeability magnetic shields require increasing control of their magnetic field environment and reductions in size, weight, power, and cost. However, magnetic fields generated by active components are distorted by high-permeability magnetic shielding, particularly when they are close to the shield’s surface. Here, we present an efficient design methodology for creating desired static magnetic field profiles by using discrete coils electromagnetically coupled to a cylindrical passive magnetic shield. We utilize a modified Green’s function solution that accounts for the interior boundary conditions on a closed finite-length high-permeability cylindrical magnetic shield and determine simplified expressions when a cylindrical coil approaches the interior surface of the shield. We use an analytic formulation of simple discrete building blocks to provide a complete discrete coil basis to generate any physically attainable magnetic field inside the shield. We then use a genetic algorithm to find optimized discrete coil structures composed of this basis. We use our methodology to generate an improved linear axial gradient field, [Formula: see text], and a transverse bias field, [Formula: see text]. These optimized structures generate the desired fields with less than [Formula: see text] error in volumes seven and three times greater in spatial extent than equivalent unoptimized standard configurations. This coil design method can be used to optimize active–passive magnetic field shaping systems that are compact and simple to manufacture, enabling accurate control of magnetic field changes in spatially confined experiments at low cost.
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Sasada, Ichiro. "Characteristics of Cylindrical Magnetic Shields." IEEJ Transactions on Fundamentals and Materials 121, no. 12 (2001): 1062–65. http://dx.doi.org/10.1541/ieejfms1990.121.12_1062.

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Dissertations / Theses on the topic "Magnetic shields"

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BAVASTRO, DAVIDE. "Modeling and design of magnetic shields for electrical Installations." Doctoral thesis, Politecnico di Torino, 2014. http://hdl.handle.net/11583/2538889.

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Nowadays, the issue of human exposure to electric and magnetic fields is still of worldwide interest [1] [2]. Several institutions investigated this problem trying to define as precisely as possible the effect of the electromagnetic field on the human health. One of the most relevant institution is the International Commission on Non-Ionizing Radiation Protection (ICNIRP) [3]. It is the view of ICNIRP that there is no currently existing scientific evidence that prolonged exposure to electromagnetic field produces possible long-term effect [4], [5]. Therefore, it focused the attention only on the well-established relations between short term direct biophysical effects producing guidelines that suggest the proper limit depending on the field frequency or on the shape of pulsing magnetic field [6] . These limitations are also published in the European Directive 2004/40/EC, [7] that regulates the maximum admissible levels for professional exposures. On the other hand, the protection of population is not homogeneous [2], [8], [9] but, usually a higher degree of safety is introduced considering stricter limits. For the above reasons the emissions of the electrical infrastructures for electricity distributions need to be analyzed.
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MANCA, MICHELE. "Active shield for low-frequency magnetic fields." Doctoral thesis, Politecnico di Torino, 2015. http://hdl.handle.net/11583/2596361.

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The magnetic field generated by power-frequency electrical installations has provoked concern in recent decades. One solution for a strong mitigation of the magnetic field is the use of an active shielding system. This technique consists in a suitable current driven in a suitable conductive loop in order to generate an opposite magnetic field. The research project has been focused on the improvement of the aspects related to the implementation, the control, and the costs of active shield. A new control strategy has been developed in order to extend the possibilities to apply this technique and to improve the actual performances. A prototype which implements the control strategy has been developed and successfully tested. Moreover, some comparisons between active and passive shields have been performed.
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Ніколенко, Богдан Миколайович. "Електромагнітні екрани для надвисокочастотних полів." Master's thesis, Київ, 2018. https://ela.kpi.ua/handle/123456789/25889.

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Актуальність теми: екранування надвисокочастотних електромагнітних полів завад є важливим завданням фізичного захисту та підвищення електромагнітної сумісності радіоелектронної апаратури. Мета дослідження: визначення матеріалів, що найкращі для використання у електромагнітних екранах для придушення надвисокочастотних завад. Об'єкт дослідження: електромагнітні екрани. Предмет дослідження: ефективність екранування з оцінкою коефіцієнтів екранування. Наукова новизна одержаних результатів: наукова новизна полягає у підвищенні ефективності екранування апаратури від електромагнітних завад надвисокої частоти шляхом конструювання екранів у вигляді трьох шарів різнотипних металів (магнітного та немагнітного), коли проміжний шар магнітний, а граничні — немагнітні. Окрім того, тришаровий екран суттєво підвищує коефіцієнт екранування за рахунок збільшення ефективності механізму відбиття електромагнітної хвилі від границь шарів. Публікації: Ніколенко Б. М. Електромагнітні екрани для надвисокочастотних полів / Комп'ютерне моделювання та оптимізація складних систем (КМОСС-2018): матеріали IV Міжнародної науково-технічної конференції / ДВНЗ "УДХТУ". - Дніпро: Баланс-клуб, 2018. - с. 91 - 93.
Relevance of the topic: Shielding of ultrahigh frequency electromagnetic interference fields is an important task of physical protection and electromagnetic compatibility improvement in radio electronic devices. Research purpose: the defining of materials the best to use in electromagnetic shields for ultrahigh frequency interferences rejecting. Object of research: electromagnetic shields. Subject of research: shielding efficiency with shielding factor estimation. Scientific novelty: scientific novelty lies in improving the efficiency of equipment shielding from electromagnetic ultrahigh frequency interferences. It is doing by constructing the shields as three layers of different types of metals (magnetic and nonmagnetic), when the intermediate layer is magnetic and the boundary layers are nonmagnetic. Furthermore, the three-layer shield greatly increases the shielding factor by raising the mechanism of efficiency by reflection of the electromagnetic wave from layer boundaries. Publications: Ніколенко Б. М. Електромагнітні екрани для надвисокочастотних полів / Комп'ютерне моделювання та оптимізація складних систем (КМОСС-2018): матеріали IV Міжнародної науково-технічної конференції / ДВНЗ "УДХТУ". - Дніпро: Баланс-клуб, 2018. - с. 91 - 93.
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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.

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Дисертація на здобуття наукового ступеня кандидата технічних наук (доктора філософії) за спеціальністю 05.09.05 – теоретична електротехніка. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2019. Дисертація присвячена розвитку методів вирішення задачі фізико-математичного моделювання та розрахунку магнітного поля (МП) високовольтних трифазних кабельних ліній (КЛ), виконаних з одножильних кабелів, при двосторонньому заземленні їх екранів. Для високовольтної трифазної КЛ запропоновано фізико-математичну модель, що дозволяє виконувати розрахунок МП КЛ і струмів в екранах за будь-якої схеми прокладання кабелів. Отримано вирази для коефіцієнта екранування МП КЛ при прокладанні кабелів "у площині" і "у трикутник" та, з використанням перетворення Кларк, наближений компактний вираз при прокладанні кабелів "у площині", похибка якого не перевищує 5%. Теоретично обґрунтовано та експериментально підтверджено можливість 2-4-кратного підвищення коефіцієнта екранування МП КЛ при двосторонньому заземленні екранів кабелів шляхом охоплення кабелів КЛ феромагнітними осердями. Отримано вирази для розрахунку коефіцієнта екранування в залежності від параметрів феромагнітних осердь, параметрів кабелів і схеми їх прокладання. Виконано верифікацію запропонованої фізико-математичної моделі та розрахункових співвідношень шляхом чисельного моделювання та на основі експерименту. Розроблено методику розрахунку МП КЛ та діючих значень струмів в екранах при двосторонньому заземленні власних екранів кабелів.
Thesis 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.
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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.

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Дисертація на здобуття наукового ступеня кандидата технічних наук (доктора філософії) за спеціальністю 05.09.05 – теоретична електротехніка. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2019. Дисертація присвячена розвитку методів вирішення задачі фізико-математичного моделювання та розрахунку магнітного поля (МП) високовольтних трифазних кабельних ліній (КЛ), виконаних з одножильних кабелів, при двосторонньому заземленні їх екранів. Для високовольтної трифазної КЛ запропоновано фізико-математичну модель, що дозволяє виконувати розрахунок МП КЛ і струмів в екранах за будь-якої схеми прокладання кабелів. Отримано вирази для коефіцієнта екранування МП КЛ при прокладанні кабелів "у площині" і "у трикутник" та, з використанням перетворення Кларк, наближений компактний вираз при прокладанні кабелів "у площині", похибка якого не перевищує 5%. Теоретично обґрунтовано та експериментально підтверджено можливість 2-4-кратного підвищення коефіцієнта екранування МП КЛ при двосторонньому заземленні екранів кабелів шляхом охоплення кабелів КЛ феромагнітними осердями. Отримано вирази для розрахунку коефіцієнта екранування в залежності від параметрів феромагнітних осердь, параметрів кабелів і схеми їх прокладання. Виконано верифікацію запропонованої фізико-математичної моделі та розрахункових співвідношень шляхом чисельного моделювання та на основі експерименту. Розроблено методику розрахунку МП КЛ та діючих значень струмів в екранах при двосторонньому заземленні власних екранів кабелів.
Thesis 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.
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Mattsson, Håkan Johannes. "Magnetic anisotropy and paleomagnetism of precambrian rocks in the Fennoscandian shield /." Luleå, 2001. http://epubl.luth.se/1402-1544/2001/32/index.html.

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Choi, Tin Chau. "An ultra-wideband magnetic-electric dipole antenna and a shielded slot antenna." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ38622.pdf.

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Mohammad, Mostak. "Optimization of Inductive Wireless Charging Systems for Electric Vehicles: Minimizing Magnetic Losses and Limiting Electromagnetic Field Emissions." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1564756659521461.

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Lu, Ming. "Synergetic Attenuation of Stray Magnetic Field in Inductive Power Transfer." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/78621.

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Significant stray magnetic field exists around the coils when charging the electric vehicles (EVs) with inductive power transfer (IPT), owning to the large air gap between the transmitter and receiver. The methods for field attenuation usually introduce extra losses and reduce the efficiency. This study focuses on the synergetic attenuation of stray magnetic field which is optimized simultaneously with the efficiency. The optimization is realized with Pareto front. In this dissertation, three methods are discussed for the field attenuation. The first method is to tune the physical parameters of the winding, such as the inner radii, outer radii, distribution of the turns, and types of the litz wires. The second method is to add metal shields around the IPT coils, in which litz wires are used as shields to reduce the shielding losses. The third method is to control the phases of winding currents, which avoids increasing the size and weight of the IPT coils. To attenuate the stray magnetic field by tuning the physical parameters, the conventional method is to sweep all the physical parameters in finite-element simulation. This takes thousands of simulations to derive the Pareto front, and it's especially time-consuming for three-dimensional simulations. This dissertation demonstrates a faster method to derive the Pareto front. The windings are replaced by the lumped loops. As long as the number of turns for each loop is known, the efficiency and magnetic field are calculated directly from the permeance matrices and current-to-field matrices. The sweep of physical parameters in finite-element simulation is replaced by the sweep of the turns numbers for the lumped loops in calculation. Only tens of simulations are required in the entire procedure, which are used to derive the matrices. An exemplary set of coils was built and tested. The efficiency from the matrix calculation is the same as the experimental measurement. The difference for stray magnetic field is less than 12.5%. Metal shields attenuate the stray magnetic field effectively, but generates significant losses owning to the uneven distribution of shield currents. This dissertation uses litz wires to replace the conventional plate shield or ring shield. Skin effect is eliminated so the shield currents are uniformly distributed and the losses are reduced. The litz shields are categorized to two types: shorted litz shield and driven litz shield. Circuit models are derived to analyze their behaviors. The concept of lumped-loop model is applied to derive the Pareto front of efficiency versus stray magnetic field for the coils with litz shield. In an exemplary IPT system, coils without metal shield and with metal shields are optimized for the same efficiency. Both the simulation and experimental measurement verify that the shorted litz shield has the best performance. The stray magnetic field is attenuated by 65% compared to the coils without shield. This dissertation also introduces the method to attenuate the stray magnetic field by controlling the phases of winding currents. The magnetic field around the coils is decomposed to the component in the axial direction and the component in the radial direction. The axial component decreases with smaller phase difference between windings' currents, while the radial component exhibits the opposite property. Because the axial component is dominant around the IPT coils, decreasing the phase difference is preferred. The dual-side-controlled converter is applied for the circuit realization. Bridges with active switches are used for both the inverter on the transmitter side and the rectifier on the receiver side. The effectiveness of this method was verified both in simulation and experiment. Compared to the conventional series-series IPT with 90° phase difference between winding currents, stray magnetic field was attenuated by up to 30% and 40% when the phase differences of winding currents are 50° and 40°, respectively. Furthermore, an analytical method is investigated to calculate the proximity-effect resistance of the planar coils with ferrite plate. The objective of this method is to work together with the fast optimization which uses the lumped-loop model. The existence of the ferrite plate complicates the calculation of the magnetic field across each turn which is critical to derive the proximity-effect resistance. In this dissertation, the ferrite plate is replaced by the mirrored turns according to the method of image. The magnetic fields are then obtained from Ampere's Law and Biot-Savart Law. Up to 200 kHz, the difference of the proximity-effect resistance is less than 15% between calculation and measurement.
Ph. D.
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McGrail, Scott Alan. "Hollow Plume Mitigation of a High-Efficiency Multistage Plasma Thruster." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1133.

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Since 2000, a relatively new electric thruster concept has been in research, development, and production at Thales Electron Devices in Germany. This High Efficiency Multistage Plasma Thruster, or HEMPT, has promising lifetime capabilities due to its plasma confinement system. However, the permanent magnet system that offers this and other benefits also creates a hollow plume, where ions are accelerated at angles rather than up the thruster centerline, causing a dip in ion current along the centerline. A laboratory model, built at JPL, was run at Cal Poly to characterize this plume shape and implement a shield to restore a conical shape to the plume. A similar solution was used on a different type of thruster, a cylindrical hall thruster, at Princeton with excellent results. A shield was designed to shunt the magnetic field outside the thruster, where the Princeton experiments have identified a radial magnetic field as the cause for this hollow plume. The thruster was run with and without the shield, taking measurements of the ion current in the plume using a linear probe drive. The shield fixed the plume shape, increasing centerline current by 48%, however it also had detrimental effects on thruster performance, causing a decrease in thrust, specific impulse, and cut the total efficiency in half. The shield design was reexamined and a new design has been suggested for future testing of the HEMPT to restore performance while still fixing the plume shape.
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Books on the topic "Magnetic shields"

1

United States. National Aeronautics and Space Administration., ed. Cluster: Inside earth's magnetic shield. [Washington, D.C.?: National Aeronautics and Space Administration, 1994.

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Office, General Accounting. Medicare: Performance of Blue Shield of Massachusetts under the tri-state contract : briefing report to congressional requesters. Washington, D.C: The Office, 1988.

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Office, General Accounting. Medicare: Laboratory fee schedules produced large beneficiary savings but no program savings : report to Congressional committees. Washington, D.C: The Office, 1987.

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Office, General Accounting. Medicare: HCFA should release data to aid consumers, prompt better HMO performance : report to congressional requesters. Washington, D.C: The Office, 1996.

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Office, General Accounting. Medicare: Change in contigency reserve funding held down increase in Part B premium : briefing report to the Chairman, Special Committee on Aging, U.S. Senate. Washington, D.C: The Office, 1987.

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Office, General Accounting. Medicare: Past overuse of intensive care services inflates hospital payments : report to the Secretary of Health and Human Services. Washington, D.C: The Office, 1986.

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Office, General Accounting. Medicare: Fewer and lower cost beneficiaries with chronic conditions enroll in HMOs : report to the chairman, Subcommittee on Health, Committee on Ways and Means, House of Representatives. Washington, D.C: The Office, 1997.

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Office, General Accounting. Medicare: Simplified processing of deceased beneficiaries' claims to be implemented : report to the chairman, Committee on Appropriations, House of Representatives. Washington, D.C: The Office, 1988.

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Office, General Accounting. Medicare: Internal controls over electronic claims for anesthesia services are inadequate : report to the Acting Administrator, Health Care Financing Administration, Department of Health and Human Services. Washington, D.C: The Office, 1989.

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Office, General Accounting. Medicare: Program provisions and payments discourage hospice participation : report to the Subcommittee on Health, Committee on Ways and Means, House of Representatives. Washington, D.C: The Office, 1989.

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Book chapters on the topic "Magnetic shields"

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Keller, Reto B. "Shielding." In Design for Electromagnetic Compatibility--In a Nutshell, 211–33. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-14186-7_13.

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AbstractIn the field of EMC, shields are used to: Reduce electromagnetic emissions from a product. Increase immunity against electric, magnetic, and/or electromagnetic radiation. The shielding theory presented in this book is based on the accepted shielding theory for electromagnetic waves, initially proposed by Schelkunoff ((1943) Electromagnetic waves. D. van Nostrand Company Inc, New York, pp 303–312) in 1943. The formulas in this chapter are approximations for shields with high electrical conductivity. Before we jump into the theory of shielding, here are two practical pieces of advice: Cables and wires. Every single signal which enters and/or leaves a shielded enclosure must be filtered or shielded. In case the cable is shielded, contact the cable shield 360∘ with the shielded enclosure. Slots and apertures. Slots and apertures reduce the shielding effectiveness SE or even lead to higher emissions than without the shield in case of resonances inside a shielding enclosure Hubing ((2021) EMC Question of the Week: 2017–2020. LearnEMC, LLC, Stoughton). If the linear dimension l [m] of a slot or aperture is larger than λ∕2, the shield is assumed to be useless Ott ((2009) Electromagnetic compatibility engineering. Wiley, New York).
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Suuroja, Sten, Tarmo All, Jüri Plado, and Kalle Suuroja. "Geology and Magnetic Signatures of the Neugrund Impact Structure, Estonia." In Impacts in Precambrian Shields, 277–94. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-662-05010-1_11.

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Hasegawa, K., H. Itozaki, and H. Kado. "Open Type Magnetic Shields by High Tc Superconducting Cylinders." In Advances in Superconductivity VIII, 1357–60. Tokyo: Springer Japan, 1996. http://dx.doi.org/10.1007/978-4-431-66871-8_305.

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Shimbo, Yukio, Kazumoto Niki, Makoto Kabasawa, and Kyoji Tachikawa. "High-Tc Magnetic Shields Prepared by a Low Pressure Plasma Spray." In Advances in Cryogenic Engineering Materials, 253–60. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4757-9053-5_34.

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Hasegawa, K., H. Itozaki, and H. Kado. "Open Type Magnetic Shields by High Tc Superconducting Cylinders and High-permeability Cylinders." In Advances in Superconductivity VII, 1305–8. Tokyo: Springer Japan, 1995. http://dx.doi.org/10.1007/978-4-431-68535-7_297.

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Tachikawa, K., O. Tsukamoto, Y. Shimbo, K. Niki, M. Ono, M. Kabasawa, and S. Kosuge. "Preparation of High-Tc Superconducting Magnetic Shields by a Low Pressure Plasma Spraying." In Advances in Biomagnetism, 749–52. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4613-0581-1_169.

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Dolan, Thomas J., Lester M. Waganer, and Mario Merola. "First Wall, Blanket, and Shield." In Magnetic Fusion Technology, 233–311. London: Springer London, 2013. http://dx.doi.org/10.1007/978-1-4471-5556-0_6.

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Pavese, F., E. Bergadano, M. Bianco, D. Ferri, D. Giraudi, and M. Vanolo. "Progress in Fabrication of Large Magnetic Shields by Using Extended YBCO Thick Films Sprayed on Stainless Steel with the HVOF Technique." In Advances in Cryogenic Engineering Materials, 917–22. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4757-9059-7_121.

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Sheng, Jingwei, Dongxu Li, Shuangai Wan, Jie Qin, and Jia-Hong Gao. "Supine OPM-MEG in Multilayer Cylindrical Shield." In Flexible High Performance Magnetic Field Sensors, 49–62. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-05363-4_4.

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Minty, Michiko G., and Frank Zimmermann. "Collimation." In Particle Acceleration and Detection, 141–47. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-662-08581-3_6.

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AbstractParticles at large betatron amplitudes or with a large momentum error constitute what is generally referred to as a beam halo. Such particles are undesirable since they produce a background in the particle-physics detector. The background arises either when the halo particles are lost at aperture restrictions in the vicinity of the detector, producing electro-magentic shower or muons, or when they emit synchrotron radiation that is not shielded and may hit sensitive detector components. In superconducting hadron storage rings, a further concern is localized particle loss near one of the superconducting magnets, which may result in the quench of the magnet, i.e., in its transition to the normalconducting state.
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Conference papers on the topic "Magnetic shields"

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Trenkel, Christian. "Saturated high permeability magnetic shields." In 2016 ESA Workshop on Aerospace EMC (Aerospace EMC). IEEE, 2016. http://dx.doi.org/10.1109/aeroemc.2016.7504587.

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Chen, H., Y. Du, and Q. Cheng. "Fast Surrogate-Assisted Design of Multilayered Magnetic Shields." In 2018 IEEE International Magnetic Conference (INTERMAG). IEEE, 2018. http://dx.doi.org/10.1109/intmag.2018.8508107.

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Greshnyakov, G., N. Korovkin, and N. Silin. "Magnetic shields special design for power cables." In 2017 International Conference on Industrial Engineering, Applications and Manufacturing (ICIEAM). IEEE, 2017. http://dx.doi.org/10.1109/icieam.2017.8076267.

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Canova, Aldo, Fabio Freschi, Luca Giaccone, and Maurizio Repetto. "Optimal design of closed multilayer magnetic shields." In 2017 International Applied Computational Electromagnetics Society Symposium - Italy (ACES). IEEE, 2017. http://dx.doi.org/10.23919/ropaces.2017.7916413.

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Bologna, M., R. Giannetti, M. Marracci, and B. Tellini. "Measuring the Magnetic Field Attenuation of Nonlinear Shields." In IEEE Instrumentation and Measurement Technology Conference. IEEE, 2006. http://dx.doi.org/10.1109/imtc.2006.328538.

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M. Bologna. "Measuring the Magnetic Field Attenuation of Nonlinear Shields." In 2006 IEEE Instrumentation and Measurement Technology. IEEE, 2006. http://dx.doi.org/10.1109/imtc.2006.237130.

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Araneo, R., G. Lovat, S. Celozzi, and P. Burghignoli. "Time domain magnetic shielding performance of thin shields." In 2017 IEEE International Conference on Environment and Electrical Engineering and 2017 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe). IEEE, 2017. http://dx.doi.org/10.1109/eeeic.2017.7977878.

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PAN, Zheng, Yue-bo LI, Jian ZHAO, Sheng JIA, and Zheng-yu HUANG. "Shielding Effectiveness of Shields and Their Combined Double-layer Shields for Low Frequency Pulsed Magnetic Field." In 2019 IEEE International Conference on Computational Electromagnetics (ICCEM). IEEE, 2019. http://dx.doi.org/10.1109/compem.2019.8779048.

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Araneo, R., G. Lovat, S. Celozzi, and P. Burghignoli. "Time-domain magnetic shielding effectiveness of planar stratified shields." In 2018 International Applied Computational Electromagnetics Society Symposium (ACES). IEEE, 2018. http://dx.doi.org/10.23919/ropaces.2018.8364187.

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Tyagi, Anand K., and T. P. Sharma. "YBCO-PbS Magnetic Shields for Superconducting Cryogenic Electronic Devices." In 1993 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics, 1993. http://dx.doi.org/10.7567/ssdm.1993.pd-4-3.

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Reports on the topic "Magnetic shields"

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Levinson, S., M. Erengll, J. Faust, and L. Burke. Evaluation of Magnetic Shields for Instrumented Launch Packages. Fort Belvoir, VA: Defense Technical Information Center, January 2002. http://dx.doi.org/10.21236/ada400096.

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Nicol, T., M. Roman, and S. Fulton. Thermal Shield Bowing in Long Superconducting Magnets. Office of Scientific and Technical Information (OSTI), September 1985. http://dx.doi.org/10.2172/1156264.

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Daudier, B. S., and E. J. Schwarz. An interpretation method for gravity and magnetic data for areas peripheral to the Canadian Shield. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1985. http://dx.doi.org/10.4095/120190.

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Thomas, M. D. Magnetic domains within the Rae Craton, mainland Canadian Shield, Nunavut, Northwest Territories, Saskatchewan and Alberta. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2018. http://dx.doi.org/10.4095/306635.

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Roberts, Huey A., Susan B. MacDonald, and Joseph Capobianco. Electric and Magnetic Field Coupling Through a Braided-Shield Cable: Transfer Admittance and Transfer Impedance. Fort Belvoir, VA: Defense Technical Information Center, July 1986. http://dx.doi.org/10.21236/ada171490.

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Thomas, M. D. Definition of magnetic domains within the Rae Craton, mainland Canadian Shield, Nunavut, Northwest Territories, Saskatchewan, and Alberta: their magnetic signatures and relationship to geology. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2018. http://dx.doi.org/10.4095/306561.

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Stafford, Robert B. Shielded open-circuited sample holders for dielectric and magnetic measurements of liquids and powders. Gaithersburg, MD: National Institute of Standards and Technology, 1993. http://dx.doi.org/10.6028/nist.ir.5001.

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