Journal articles: 'Magnet effects'

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Amjadian, Mohsen, and Anil K. Agrawal. "Planar arrangement of permanent magnets in design of a magneto-solid damper by finite element method." Journal of Intelligent Material Systems and Structures 31, no. 7 (February 27, 2020): 998–1014. http://dx.doi.org/10.1177/1045389x20905968.

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This article studies the energy dissipation mechanism of a proposed magneto-solid damper using a three-dimensional finite element model developed in COMSOL Multiphysics software. The energy dissipation mechanism of the magneto-solid damper dissipates energy through combined actions of friction and eddy current damping. The key components of the magneto-solid damper are a steel plate, two copper plates placed on two sides of the steel plate in parallel, and two planar arrays of permanent magnets each one placed between the steel plate and one of the copper plates. These arrays are kept away from the steel and copper plates through narrow gaps; the gaps between them and the steel plate are filled with thin friction pads made of non-magnetic materials. The attractive magnetic interaction between the permanent magnet arrays and the steel plate provides the normal force for the friction developed between the friction pads and the steel plate when the permanent magnet arrays move relative to the steel plate. The motion of the permanent magnet arrays relative to the copper plates, on the other hand, provides the eddy current damping. The main contribution of this article is to optimize the pole arrangement of the permanent magnets and demonstrate that how the optimum pole arrangement can affect the energy dissipation capacity of the magneto-solid damper. The analysis results show that, for a given number and size of the permanent magnets, alternate arrangement of the poles of permanent magnets along the direction of their motion is the most optimal case resulting in large and smooth hysteresis force–displacement loops. This pole arrangement has also been used to find the optimum size of the steel and copper plates by addressing edge and skin effects in the design of the damper.

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Sirimanna, Samith, Thanatheepan Balachandran, and Kiruba Haran. "A Review on Magnet Loss Analysis, Validation, Design Considerations, and Reduction Strategies in Permanent Magnet Synchronous Motors." Energies 15, no. 17 (August 23, 2022): 6116. http://dx.doi.org/10.3390/en15176116.

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Eddy current losses in magnets are a major consideration in the rotor design of permanent magnet synchronous motors (PMSMs). Stator design choices and the use of modern inverters with high switching frequency introduce harmonics that can contribute to significant losses in the magnets, causing the rotor to heat up. In typical PMSMs, the lack of rotor cooling can cause the magnet’s performance to degrade at high temperatures and eventually demagnetize. This review examines a large number of studies analyzing magnet eddy current losses using analytical methods and finite-element analysis. In some of these studies, magnet segmentation is carried out to reduce the losses; however, their loss-reduction effects depend highly on the type of PMSM and the mix of stator harmonics. Magnet segmentation without considering these effects can, in fact, increase the magnet losses, in addition to the extra manufacturing efforts. Multiple design analysis show the influence of rotor–stator geometric features on magnet losses. Although measuring magnet eddy current losses for these motor designs is a tedious task, authors have proposed calorimetric and loss segregation-based techniques to provide validation. This paper addresses magnet loss modeling techniques, PM material considerations, magnet segmentation effectiveness, motor and stator design effects, and experimental validation to inform motor designers about the costs and benefits of rotor designs that minimize rotor losses.

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Qin, Wan Zhong. "The Mold for Bonded NdFeB Magnet Compression Molding." Applied Mechanics and Materials 633-634 (September 2014): 747–50. http://dx.doi.org/10.4028/www.scientific.net/amm.633-634.747.

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Compression molding is the most important method to gain high quality bonded NdFeB magnets. The production process is preparation of composite powder, compression molding, coating and magnetizing. Based on test and lot production practice, the important effects of compression molding actions, mould structure and mould material on magnet quality are analyzed. The mold structures for ring-magnet and arc-magnet are fixed. The key techniques that controlling the quality of bonded NdFeB magnets are summarized.

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WEBER, HARALD W. "RADIATION EFFECTS ON SUPERCONDUCTING FUSION MAGNET COMPONENTS." International Journal of Modern Physics E 20, no. 06 (June 2011): 1325–78. http://dx.doi.org/10.1142/s0218301311018526.

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Nuclear fusion devices based on the magnetic confinement principle heavily rely on the existence and performance of superconducting magnets and have always significantly contributed to advancing superconductor and magnet technology to their limits. In view of the presently ongoing construction of the tokamak device ITER and the stellerator device Wendelstein 7X and their record breaking parameters concerning size, complexity of design, stored energy, amperage, mechanical and magnetic forces, critical current densities and stability requirements, it is deemed timely to review another critical parameter that is practically unique to these devices, namely the radiation response of all magnet components to the lifetime fluence of fast neutrons and gamma rays produced by the fusion reactions of deuterium and tritium. I will review these radiation effects in turn for the currently employed standard "technical" low temperature superconductors NbTi and Nb 3 Sn , the stabilizing material ( Cu ) as well as the magnet insulation materials and conclude by discussing the potential of high temperature superconducting materials for future generations of fusion devices, such as DEMO.

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Ichimura, Yoshihiro, Hideki Takezawa, and Naotake Mohri. "Relationship between Magnetic Flux Density and Temperature Distributions of Permanent Magnets by EDM." Key Engineering Materials 523-524 (November 2012): 322–27. http://dx.doi.org/10.4028/www.scientific.net/kem.523-524.322.

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It is difficult to machine permanent magnets by traditional machining such as turning, milling and grinding, because of magnetic force. However, electrical discharge machining (EDM), which is a non-contact thermal machining method, has been used for shape machining of magnetic materials. In the EDM process, non-magnetic materials such as copper and graphite are typically used for electrodes. Magnetic materials have a Curie point; therefore, their magnetic flux density reduces when they are heated to a high temperature. Because EDM is a thermal process, it has the potential to control the magnetic flux density of a machined surface. In this study, to clarify the relationship between magnetic flux density and temperature distributions in depth direction of permanent magnest by EDM, internal temperatures of magnets were investigated using a K type thermo couple during EDM. Neodymium magnets were used as work-pieces. The magnetic flux density of a machined neodymium magnet was measured. In addition, the effects of duty factor (D.F.) were also examined. The results showed that the average temperature inside of the magnet is determined by the input energy, depending on the discharge conditions. A decrease of surface magnetic flux density after EDM is affected by the magnitude of the area and the amount of decrease is due to the increase of the internal temperature of the magnet. Therefore, it isn’t determined by the magnitude of the simple input energy.

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Palagummi, Sri Vikram, and Fuh-Gwo Yuan. "An enhanced performance of a horizontal diamagnetic levitation mechanism–based vibration energy harvester for low frequency applications." Journal of Intelligent Material Systems and Structures 28, no. 5 (July 28, 2016): 578–94. http://dx.doi.org/10.1177/1045389x16651152.

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This article identifies and studies key parameters that characterize a horizontal diamagnetic levitation mechanism–based low frequency vibration energy harvester with the aim of enhancing performance metrics such as efficiency and volume figure of merit. The horizontal diamagnetic levitation mechanism comprises three permanent magnets and two diamagnetic plates. Two of the magnets, lifting magnets, are placed co-axially at a distance such that each attracts a centrally located magnet, floating magnet, to balance its weight. This floating magnet is flanked closely by two diamagnetic plates which stabilize the levitation in the axial direction. The influence of the geometry of the floating magnet, the lifting magnet, and the diamagnetic plate is parametrically studied to quantify their effects on the size, stability of the levitation mechanism, and the resonant frequency of the floating magnet. For vibration energy harvesting using the horizontal diamagnetic levitation mechanism, a coil geometry and eddy current damping are critically discussed. Based on the analysis, an efficient experimental system is setup which showed a softening frequency response with an average system efficiency of 25.8% and a volume figure of merit of 0.23% when excited at a root mean square acceleration of 0.0546 m/s2 and at a frequency of 1.9 Hz.

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Jin, Wencan, Zhipeng Ye, Xiangpeng Luo, Bowen Yang, Gaihua Ye, Fangzhou Yin, Hyun Ho Kim, et al. "Tunable layered-magnetism–assisted magneto-Raman effect in a two-dimensional magnet CrI3." Proceedings of the National Academy of Sciences 117, no. 40 (September 23, 2020): 24664–69. http://dx.doi.org/10.1073/pnas.2012980117.

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We used a combination of polarized Raman spectroscopy experiment and model magnetism–phonon coupling calculations to study the rich magneto-Raman effect in the two-dimensional (2D) magnet CrI3. We reveal a layered-magnetism–assisted phonon scattering mechanism below the magnetic onset temperature, whose Raman excitation breaks time-reversal symmetry, has an antisymmetric Raman tensor, and follows the magnetic phase transitions across critical magnetic fields, on top of the presence of the conventional phonon scattering with symmetric Raman tensors in N-layer CrI3. We resolve in data and by calculations that the first-order Ag phonon of the monolayer splits into an N-fold multiplet in N-layer CrI3 due to the interlayer coupling (N≥2) and that the phonons within the multiplet show distinct magnetic field dependence because of their different layered-magnetism–phonon coupling. We further find that such a layered-magnetism–phonon coupled Raman scattering mechanism extends beyond first-order to higher-order multiphonon scattering processes. Our results on the magneto-Raman effect of the first-order phonons in the multiplet and the higher-order multiphonons in N-layer CrI3 demonstrate the rich and strong behavior of emergent magneto-optical effects in 2D magnets and underline the unique opportunities of spin–phonon physics in van der Waals layered magnets.

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Leesungbok, Richard, Su-Jin Ahn, Suk-Won Lee, Geon-Ho Park, Joo-Sung Kang, and Jung-Joo Choi. "The Effects of a Static Magnetic Field on Bone Formation Around a Sandblasted, Large-Grit, Acid-Etched–Treated Titanium Implant." Journal of Oral Implantology 39, S1 (May 1, 2013): 248–55. http://dx.doi.org/10.1563/aaid-joi-d-11-00101.

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The purpose of this study was to compare the bone formation around commercial sandblasted, large-grit, acid-etched (SLA)–treated titanium implants with or without a neodymium magnet in a rabbit tibia through histomorphometric analysis. Commercial SLA-treated implants with or without neodymium magnets were placed in 10 rabbits. After incising the flat part of the rabbit's tibia and installation of the specimens of titanium implants, the nonmagnet group was stitched without magnet insertion. On the other hand, the magnet group was inserted with neodymium magnet, fixed with pattern resin, and stitched. At 3 and 6 weeks after surgery, the animals were sacrificed, and the specimens were obtained. Undecalcified specimens were prepared for histomorphometric analysis of the bone-to-implant contact ratio (BIC) and bone volume (BV). The histomorphometric findings of the cortical bone showed that the mean BVs of the magnet group (3 weeks, 75.99%; 6 weeks, 82.94%) were higher than those of the nonmagnet group (3 weeks, 74.58%; 6 weeks, 78.75%), but there were no significant differences between the 2 groups (P > .05). In the marrow bone, the mean BICs of the magnet group (3 weeks, 10.36%; 6 weeks, 10.41%) were higher than those of the nonmagnet group (3 weeks, 6.41%; 6 weeks, 7.36%). After 3 weeks of installation, there was a significant difference between the 2 groups (P < .05). In rabbit tibia, the SLA-treated titanium implants with a neodymium magnet can trigger faster early peri-implant bone formation than those without a magnet.

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Kumar, Ram, Antonino La Rocca, Gaurang Vakil, David Gerada, Chris Gerada, and Baylon G. Fernandes. "Significance of Anisotropic Thermal Expansion in High Speed Electric Machines Employing NdFeB Permanent Magnets." Energies 14, no. 22 (November 12, 2021): 7558. http://dx.doi.org/10.3390/en14227558.

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Many high speed applications employ a surface permanent magnet (PM) machine topology with a retaining sleeve due to its robustness and ability to achieve high overall peripheral speeds as well as efficiencies. One often overlooked feature in the mechanical design of such machines, which has not achieved sufficient attention to date is the anisotropic thermal expansion of rare earth magnets, the degree of which varies for different magnet technologies. This paper investigates the effects of the aforementioned on the mechanical design of a high speed PM spindle machine with NdFeB magnets. The maximum allowable interference is found to be limited by the working temperature of the magnets while the minimum required interference is increased due to their anisotropic thermal expansion. Based on this, appropriate conditions are formulated to integrate a Neodymium Iron Boron (NdFeB) PM in high speed rotors. These modifications considering the shaft together with the magnet anisotropic thermal expansion are included in a proposed rotor design and validated using simulations in ANSYS mechanical environment.

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Song, Yi Lin, Shun Ping Zhang, and Shu Mei Gao. "Research of a Small-Sized Magnetic Hydro-Cylinder without Piston Rod." Key Engineering Materials 579-580 (September 2013): 259–64. http://dx.doi.org/10.4028/www.scientific.net/kem.579-580.259.

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In order to develop a device for the elderly on bed for long-term to do legs rehabilitation exercise, a small-sized magnetic hydro-cylinder without piston rod is researched. The finite element analysis software--Ansoft Maxwell and an experiment device developed by us are used to analyze and to research the magnetic coupling force performance, the effects of the arrangement of the magnet, the separation distance between the magnets and the magnet thickness on the cylinder performance. Finite element analysis and experimental results show that the cylinder wall thickness should be thinned under the premise of meeting the strength requirement, the magnets should be arranged in the reverse direction, the separation distance between the adjacent magnets should be set to 4 mm, the thickness of magnet should be set to about 10 mm. Under those conditions, the better performance of magnetic hydro-cylinder without piston rod can be gotten, and the miniaturization of the cylinder structure can be realized.

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Ohkoshi, S., K. Ikeda, J. Shimura, and K. Hashimoto. "Nonlinear Magneto-Optical Effects of Prussian blue Analog-based Magnet." Transactions of the Magnetics Society of Japan 4, no. 4-2 (2004): 266–71. http://dx.doi.org/10.3379/tmjpn2001.4.266.

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Gholamian, Seyed Asghar, and Hamid Reza Gholinejad. "A DIFFERENT APPROACH IN OPTIMUM DESIGN PROCESS AND FEA VALIDATION OF LOW-SPEED MULTI-PHASE IPMSMS." IIUM Engineering Journal 18, no. 1 (May 30, 2017): 133–45. http://dx.doi.org/10.31436/iiumej.v18i1.687.

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Magnets placement effects on permanent magnet motors performance, because of its different magnetic flux density distribution. Therefore, different types of magnet placement should be examined experimentally or by valid simulations. In this paper, first, an interior permanent magnet synchronous motor (IPMSM) called spoke type with specifications related to the propulsion of ships is designed and then optimized by ant colony algorithm to increase the torque-to-volume ratio. The design procedure and its formulas presented as simple as possible. Then, to verify the optimization results of the optimized motor, a Two-dimensional finite element analysis (FEA) is done. Also in this analyze the core and the slot saturation was studied.

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Wu, Shasha, Baojian Wang, Tao Zhang, and Quanhao Gu. "Design Optimization and Electromagnetic Performance Analysis of an Axial-Flux Permanent Magnet Brushless DC Motor with Unequal-Thickness Magnets." Applied Sciences 12, no. 15 (August 5, 2022): 7863. http://dx.doi.org/10.3390/app12157863.

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To improve electromagnetic performance, an axial-flux permanent magnet brushless DC motor (AFPMBLDCM) with unequal-thickness arc permanent magnets is proposed in this paper. Firstly, the structure and magnetic circuit of the AFPMBLDCM with unequal-thickness arc permanent magnets were designed. Then, the mathematical models and design method of the main parameters were derived. According to the rated power and rated speed, the main parameters were further designed, and the analytical model was established by using Maxwell 3D. The air-gap flux density, back electromotive force (EMF) and torque under no-load and load conditions were calculated and analyzed to verify the validity of the model and design. Finally, based on a parameter scanning optimization method, the effects of the permanent magnet thickness, pole arc coefficient and permanent magnet radius on cogging torque were analyzed. The optimized parameters of the AFPMBLDCM with unequal-thickness arc permanent magnets were obtained. The results show that the sinusoidal degree of the air-gap magnetic field is improved, and the maximum torque ripple of the AFPMBLDCM is reduced to 2.92%.

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Kaluvagunta, D. C., and B. Fahimi. "Three-dimensional magnetic effects in permanent-magnet magnet synchronous machines." IEEE Transactions on Magnetics 41, no. 8 (August 2005): 2398–405. http://dx.doi.org/10.1109/tmag.2005.852944.

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Lei, Yi Ming, and Zhi Yu Wen. "Numerical Optimization Approach of the Gap between the Magnet and Coil for Electromagnetic Vibration Energy Harvesters Design." Key Engineering Materials 645-646 (May 2015): 1214–22. http://dx.doi.org/10.4028/www.scientific.net/kem.645-646.1214.

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In the design of the micro electromagnetic vibration harvester, an important goal is maximization of the magnetic flux linkage gradient, which directly determines the induced voltage and output power of the electromagnetic vibration harvester. This paper established a numerical model based on structure of the electromagnetic vibration energy harvester. An analytic expression for the magnetic field of rectangular permanent magnets is used to build up an electromagnetic coupling model. The magnetic field distribution of the rectangular permanent magnet was analyzed. The effects of the gap between the magnet and the coil on the load voltage of the electromagnetic vibration energy harvester were investigated. According to the formula, the magnetic flux linkage and flux gradient were calculated to optimize the geometrical parameter of the magnet and coil. The method and boundary conditions of optimizing the gap between the magnet and coil were presented. The maximum output voltage can be obtained by optimizing the gap between the magnet and the coil. A simple prototype was fabricated and measured to validate the theoretical deducing and the feasibility of method.

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Heydari, M. B., M. Asgari, L. Gharib, A. Keshtkar, N. Jafari, and M. Zolfaghari. "A Novel Augmented Railgun Using Permanent Magnets." Advanced Electromagnetics 8, no. 1 (June 9, 2019): 99–105. http://dx.doi.org/10.7716/aem.v8i1.961.

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A novel augmented railgun using a permanent magnet is proposed in this paper. The effects of the permanent magnet on the magnetic field and distribution of current density have been investigated. High current densities in the railguns can lead to high local temperature and erosion of the rails. Therefore, the current densities in the rails and armature should be decreased without the reduction of the Lorentz force which is required for acceleration. For this purpose, augmentation of the magnetic field can be used as an effective method. The Finite Element Method (FEM) simulations have been applied in this article to analyze the performance of the railgun in the presence of the magnets. Two augmented railgun structures have been introduced to produce a constant external magnetic field. For both structures, augmented railgun characteristics are studied in comparison to the railgun without the augmentation. The results show that augmentation with permanent magnet increases railgun efficiency, especially in low current railguns. For pulse current source I=30kA, Lorentz force of the augmented railgun with four magnets is 2.02 times greater than the conventional railgun.

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Wijaya, Fransisco Danang, Budi Azhari, and Harnoko Stephanus. "Optimum Permanent Magnets Configuration in Flat-Quasi Linear Permanent Magnet Generators." International Journal of Electrical and Computer Engineering (IJECE) 6, no. 6 (December 1, 2016): 2589. http://dx.doi.org/10.11591/ijece.v6i6.11966.

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Flat-quasi type of linear permanent magnet generators (LPMGs) have been considered to be applied for several applications, such for wave energy conversion and free piston combustion engine. One of the important issues concerning LPMG is the permanent magnets configuration, due to its effects to the generator’s excitation performance. In this paper, a 1 kW flat-quasi LPMG would be designed and built. During the process, optimum permanent magnets configuration was required and researched. The optimum configuration considered the output power and resulted cogging force. Invetigation was then conducted by modifying several variables, including poles’ arrangement, pole length, number of pole, and pole skewing angle. The modification constraints were total permanent magnets’ volume and generator dimension. The results showed that permanent magnet configuration with halbach arrangement, pole length equals 55% of the slot pitch length, and 61.19o skewing angle produced the optimum output values.

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Wijaya, Fransisco Danang, Budi Azhari, and Harnoko Stephanus. "Optimum Permanent Magnets Configuration in Flat-Quasi Linear Permanent Magnet Generators." International Journal of Electrical and Computer Engineering (IJECE) 6, no. 6 (December 1, 2016): 2589. http://dx.doi.org/10.11591/ijece.v6i6.pp2589-2602.

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Flat-quasi type of linear permanent magnet generators (LPMGs) have been considered to be applied for several applications, such for wave energy conversion and free piston combustion engine. One of the important issues concerning LPMG is the permanent magnets configuration, due to its effects to the generator’s excitation performance. In this paper, a 1 kW flat-quasi LPMG would be designed and built. During the process, optimum permanent magnets configuration was required and researched. The optimum configuration considered the output power and resulted cogging force. Invetigation was then conducted by modifying several variables, including poles’ arrangement, pole length, number of pole, and pole skewing angle. The modification constraints were total permanent magnets’ volume and generator dimension. The results showed that permanent magnet configuration with halbach arrangement, pole length equals 55% of the slot pitch length, and 61.19o skewing angle produced the optimum output values.

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He, Xin Zhi, De Cai Li, Wen Ming Yang, and Hai Na Zhang. "Experimental Study on the Second-Order Buoyancy of Magnetic Fluid." Key Engineering Materials 512-515 (June 2012): 1464–69. http://dx.doi.org/10.4028/www.scientific.net/kem.512-515.1464.

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The buoyancy principle of magnetic fluid is one of the most attractive effects of magnetic fluid statics. But it is too difficult to calculate the buoyancy directly due to the complexity of magnetic field. Moreover, numerical calculation employs too many assumptions. So in this paper the experimental method is adopted to measure the second-order buoyancy received by permanent magnet immersed in magnetic fluid, which depends on the distance between the magnet and the wall of vessel. The influence of the diameter of cylindrical vessels, the size of magnets and the saturation magnetization of magnetic fluid on the buoyancy is also analyzed qualitatively.

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Qin, Wan Zhong, Jie He, and Ling Yi Yao. "Research on the Molding Technology of Bonded NdFeB Magnets." Applied Mechanics and Materials 217-219 (November 2012): 1815–18. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.1815.

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For the composite powders with different NdFeB powder content , the effects of processing parameters including injection temperature, injection pressure, holding pressure and injection velocity on the sizes and properties of injection molded bonded NdFeB magnet were investigated, and the reasons of effects were also analyzed. The results show that changes in injection parameters can influence the size, density, mechanical properties and magnetic properties of bonded NdFeB magnets, and has strong influence regularity. The injection temperature and injection pressure have the greatest impact on the performance. On the basis of research, the injection molding bonded NdFeB magnet with high performance is obtained with magnetic properties Br=0.539T, Hcb=345.37kA/m, Hci=681.02kA/m, (BH)max=47.37kJ/m3 and density 5.07g/cm3 respectively.

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Strahan, R. J., and D. B. Watson. "Effects of airgap and magnet shapes on permanent magnet reluctance torque." IEEE Transactions on Magnetics 35, no. 1 (1999): 536–42. http://dx.doi.org/10.1109/20.737478.

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Kuipers, Nathan T., Charity L. Sauder, and Chester A. Ray. "Influence of static magnetic fields on pain perception and sympathetic nerve activity in humans." Journal of Applied Physiology 102, no. 4 (April 2007): 1410–15. http://dx.doi.org/10.1152/japplphysiol.00734.2006.

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Static and pulsed magnetic fields have been reported to have a variety of physiological effects. However, the effect of static magnetic fields on pain perception and sympathetic function is equivocal. To address this question, we measured pain perception during reproducible noxious stimuli during acute exposure to static magnets. Pain perception, muscle sympathetic nerve activity, mean arterial pressure, heart rate, and forearm blood velocity were measured during rest, isometric handgrip, postexercise muscle ischemia, and cold pressor test during magnet and placebo exposure in 15 subjects (25 ± 1 yr; 8 men and 7 women) following 1 h of exposure. During magnet exposure, subjects were placed on a mattress with 95 evenly spaced 0.06-T magnets imbedded in it. During placebo exposure, subjects were placed on an identical mattress without magnets. The order of the two exposure conditions was randomized. At rest, no significant differences were noted in muscle sympathetic nerve activity (8 ± 1 and 7 ± 1 bursts/min for magnet and placebo, respectively), mean arterial pressure (91 ± 3 and 93 ± 3 mmHg), heart rate (63 ± 2 and 62 ± 2 beats/min), and forearm blood velocity (3.0 ± 0.3 and 2.6 ± 0.3 cm/s). Magnets did not alter pain perception during the three stimuli. During all interventions, no significant differences between exposure conditions were found in muscle sympathetic nerve activity and hemodynamic measurements. These results indicate that acute exposure to static magnetic fields does not alter pain perception, sympathetic function, and hemodynamics at rest or during noxious stimuli.

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Meyer, Alexander, Christoph Ringelhan, Carina Fischer, and Jörg Franke. "Energy Efficient Strategies for Processing Rare Earth Permanent Magnets." Applied Mechanics and Materials 856 (November 2016): 195–200. http://dx.doi.org/10.4028/www.scientific.net/amm.856.195.

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Due to high magnetic fields causing strong interactions between permanent magnets and other ferromagnetic material, transport and handling of magnetized magnet bodies is challenging. To avoid undesired effects, such as influences on sensitive devices or difficult separation of the single magnets from stack, spacing and shielding of the magnet bodies is required leading to larger package sizes and thus in some cases higher energy demand during transport referred to the transported magnet mass. An optimization of the transport chain can be reached using the software tool presented in this paper. Further magnetizing high coercive rare earth magnets needs strong magnetic fields. To create the necessary field strength, copper coils are used requiring current strengths of several kA. Since the electrical resistance of copper differs from zero, this also means enormous thermal losses. Hence to reduce the losses and to avoid thermal damage of the coil, only short current pulses are applied generated by a pulse magnetizer. However, the efficiency of the process is very poor and lies in the lower per mil range. The presented paper explains the magnetization process in detail with focus on the losses within the magnetization device. Further different material parameters influencing the saturation field strength, such as conductivity, size and diameter to length ratio are presented and possibilities to improve the energy efficiency are shown.

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Yin, Shao Hui, Yong Qiang Wang, Gao Jian Deng, Hu Luo, Feng Jun Chen, and Zhao Cheng Lu. "Effects of Permanent Magnet Excitation on Material Removal Rate in Area Taking Magnetorhelogical Finishing." Advanced Materials Research 797 (September 2013): 401–4. http://dx.doi.org/10.4028/www.scientific.net/amr.797.401.

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In this paper, a novel area taking MRF process using permanent magnet as excitation was proposed. Four types of permanent magnet configurations were considered. Polishing experiment was conducted. Effects of different permanent magnet configurations on material removal rate (MRR) were discussed.

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Woo, Jong-Hyeon, Tae-Kyoung Bang, Jeong-In Lee, Hoon-Ki Lee, and Jang-Young Choi. "Experimental Verification and Analytical Approach for Electromagnetic Characteristics of a High-Speed Permanent Magnet Motor with Two Different Rotors and Winding Patterns." Applied Sciences 11, no. 19 (September 28, 2021): 9060. http://dx.doi.org/10.3390/app11199060.

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In general, high-speed machines should be designed with high efficiency electromagnetic and mechanical characteristics. It is important to analyze the electromagnetic loss for a design with high efficiency. In this study, the effects of the magneto–motive force and time harmonics of the stator current according to the winding distribution of a high-speed permanent magnet motor on the electromagnetic characteristics were comparatively analyzed using analytical methods and FEM. In addition, the final model was proposed by analyzing the relationship between the magnet usage according to the rotor shape and the electromagnetic and mechanical properties according to the winding patterns. Finally, the optimal model was manufactured and the validity was experimentally verified.

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Li, Li, Guang Ming Yuan, Zong Wei Niu, and Rong Guo Hou. "Effects of Electrical Discharge Energy on Machining Performance of Sintered NdFeB Magnet." Materials Science Forum 620-622 (April 2009): 711–14. http://dx.doi.org/10.4028/www.scientific.net/msf.620-622.711.

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Sintered NdFeB permanent magnet is widely used in many areas because of its excellent magnet property. In this study, the machining parameters of electrical discharge machining (EDM) are varied to study the effects of electrical discharge energy on material removal rate and surface roughness of NdFeB magnet. Moreover, the micro-cracks on the machined surface induced by EDM are also examined. The experimental results reveal that the MRR increases with the electrical discharge energy. The number of surface cracks on the machined surface increases with the enhancement of discharge energy Thus, using EDM process to machine sintered NdFeB magnet depends on setting the machining parameters to prevent surface crack.

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Barhoumi, El Manaa, Ahmed Galal Abo-Khalil, Youcef Berrouche, and Frederic Wurtz. "Analysis and comparison of end effects in linear switched reluctance and hybrid motors." Journal of Electrical Engineering 68, no. 2 (March 28, 2017): 138–42. http://dx.doi.org/10.1515/jee-2017-0019.

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Abstract This paper presents and discusses the longitudinal and transversal end effects which affects the propulsive force of linear motors. Generally, the modeling of linear machine considers the forces distortion due to the specific geometry of linear actuators. The insertion of permanent magnets on the stator allows improving the propulsive force produced by switched reluctance linear motors. Also, the inserted permanent magnets in the hybrid structure allow reducing considerably the ends effects observed in linear motors. The analysis was conducted using 2D and 3D finite elements method. The permanent magnet reinforces the flux produced by the winding and reorients it which allows modifying the impact of end effects. Presented simulations and discussions show the importance of this study to characterize the end effects in two different linear motors.

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Bernad, Susan-Resiga, and Bernad. "Hemodynamic Effects on Particle Targeting in the Arterial Bifurcation for Different Magnet Positions." Molecules 24, no. 13 (July 9, 2019): 2509. http://dx.doi.org/10.3390/molecules24132509.

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The present study investigated the possibilities and feasibility of drug targeting for an arterial bifurcation lesion to influence the host healing response. A micrometer sized iron particle was used only to model the magnetic carrier in the experimental investigation (not intended for clinical use), to demonstrate the feasibility of the particle targeting at the lesion site and facilitate the new experimental investigations using coated superparamagnetic iron oxide nanoparticles. Magnetic fields were generated by a single permanent external magnet (ferrite magnet). Artery bifurcation exerts severe impacts on drug distribution, both in the main vessel and the branches, practically inducing an uneven drug concentration distribution in the bifurcation lesion area. There are permanently positioned magnets in the vicinity of the bifurcation near the diseased area. The generated magnetic field induced deviation of the injected ferromagnetic particles and were captured onto the vessel wall of the test section. To increase the particle accumulation in the targeted region and consequently avoid the polypharmacology (interaction of the injected drug particles with multiple target sites), it is critical to understand flow hemodynamics and the correlation between flow structure, magnetic field gradient, and spatial position.

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Nagaitsev, Sergei, and Valeri Lebedev. "A Cost-Effective Rapid-Cycling Synchrotron." Reviews of Accelerator Science and Technology 10, no. 01 (August 2019): 245–66. http://dx.doi.org/10.1142/s1793626819300135.

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The present Fermilab proton Booster is an early example of a rapid-cycling synchrotron (RCS). Built in 1960s, it features a design in which the combined-function dipole magnets serve as vacuum chambers. Such a design is quite cost-effective, and it does not have the limitations associated with the eddy currents in a metallic vacuum chamber. However, an important drawback of that design is a high impedance, as seen by a beam, because of the magnet laminations. More recent RCS designs (e.g. J-PARC) employ large and complex ceramic vacuum chambers in order to mitigate the eddy-current effects and to shield the beam from the magnet laminations. Such a design, albeit very successful, is quite costly because it requires large-bore magnets and large-bore RF cavities. In this paper, we consider an RCS concept with a thin-wall metallic vacuum chamber as a compromise between the chamber-less Fermilab Booster design and the large-bore design with ceramic chambers.

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Qin, Wan Zhong, and Jie He. "Research on Composite Powder and Magnet Properties of Bonded NdFeB Magnets Prepared by Press Molding." Applied Mechanics and Materials 345 (August 2013): 218–22. http://dx.doi.org/10.4028/www.scientific.net/amm.345.218.

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The manufacture technology and properties testing method of composite powder and bonded NdFeB magnets from press molding were described in detail. The effects of the content of binder and additives, the molding pressure, the treatment of magnet surface on the mechanical property, processing property, magnetic property and anti-oxidation property of press molding magnets were investigated. Furthermore, the effect mechanism was revealed microcosmically. The press molding bonded magnets was prepared by using the MQP-B rapidly quenching NdFeB magnetic powder and epoxy binder. The magnetic properties are: Br = 0.722 T, Hcb = 457 kA/m, Hci = 718 kA/m, and (BH) max = 83.5 kJ/m3.

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Qin, Wan Zhong, and Jie He. "Research on Bonded NdFeB Arc-Magnets." Advanced Materials Research 941-944 (June 2014): 614–18. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.614.

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The manufacture technology and mould structure of bonded NdFeB arc-magnets from press molding were described. The effects of the content of binder and additives, particle size of magnetic powder, the molding pressure, the treatment of magnet surface on the mechanical property, processing property, magnetic property and anti-oxidation property of press molding magnets were investigated. The press molding bonded magnets were prepared by using the MQP-B rapidly quenching NdFeB magnetic powder and epoxy binder. The magnetic properties are: Br = 0.722 T, Hcb = 457 kA/m, Hci = 718 kA/m, and (BH) max = 83.5 kJ/m3.

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32

Zhang, Jun Hui, Zhi Li Zhang, De Cai Li, and Jie Yao. "Effects of Magnetic Fluid on Magnetic Fluid Damper." Key Engineering Materials 512-515 (June 2012): 1479–83. http://dx.doi.org/10.4028/www.scientific.net/kem.512-515.1479.

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A magnetic fluid damper which based on the principle of second-order buoyancy of magnetic liquid has been presented. During the process of damping, besides the elastic deformation of magnetic liquid adsorbed by permanent magnet, the main ways of energy dissipation are the friction functions, which include the friction between magnets and magnetic liquid, magnetic fluid and magnetic fluid and magnetic fluid and the shell of the damper. In order to investigate influence of magnetic fluid on damping effect, a series of experiments under different magnetic fluid with related parameters including magnetic fluid volume and saturation magnetization are carried out. It is found that both volume and saturation magnetization of magnetic fluid have optimal value on the damping effect of the damper.

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33

Rudnicki, Tomasz. "Measurement of the PMSM Shaft Position with An Absolute Encoder." Electronics 8, no. 11 (October 27, 2019): 1229. http://dx.doi.org/10.3390/electronics8111229.

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The most critical aspect of assessing a permanent magnet synchronous motor is the problem of correctly measuring the position of the synchronous motor shaft. The purpose of this article was to show the effects of employing an absolute encoder to control a synchronous motor with permanent magnets while encountering disturbances. This problem is often overlooked, but it appears from time to time. The correct measurement of the shaft position eliminates improper motor operation characterized by jerking. The article showed that despite momentary erroneous readings of the shaft’s position, it was still possible to control the permanent magnet synchronous motor (PMSM). This also allows for correct measurement of the motor speed. This paper originally proposed an adaptive correction method for a rotary encoder.

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Lee, Yoon-Seok, Yeonghwan Song, Seungchan Cho, Ilguk Jo, and Moonhee Choi. "Effects of Magnetizing Yoke Design on the Magnetic Properties of Nd2Fe14B Permanent Magnet for Electric Vehicle Motor Applications." Applied Sciences 12, no. 15 (August 3, 2022): 7813. http://dx.doi.org/10.3390/app12157813.

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When the uniformity of the magnetization yoke is low, a mismatch occurs between the physical rotation center and the center due to the magnetic force after magnetization. This discrepancy in rotation can cause issues such as vibration and noise during high-speed rotation, which in the long term leads to a decrease in the lifespan of the motor. In addition, in order to minimize the problem of motor lifespan when a vehicle is used for more than 10 years after purchase, the problems caused by magnetization should be solved as far as possible. In this study, magnetization yokes were designed in various ways to optimize the factors that affect the magnetic properties after the magnetization of the Nd2Fe14B permanent magnets used in electric motors. In the case of a 50 µm deviation between the coils wound inside the magnetization yoke, the magnetic property imbalance of the Nd2Fe14B magnets and the motor characteristics are not significantly affected after magnetization. However, when the center of the coil wound inside the yoke is shifted from the center of the yoke, the magnetic field is generated unevenly, which degrades both the magnetic and motor characteristics of the Nd2Fe14B magnet. Therefore, it is very important to control the center of the coil that generates the external magnetic field in the magnetized yoke in order to magnetize the Nd2Fe14B magnet with excellent magnetic properties.

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35

Romanov, Roman A., Tatyana V. Myasnikova, and Alexey N. Matyunin. "INCREASE IN THE ELECTROMAGNETIC MOMENT OF A SUPERMINIATURE ELECTRIC MOTOR EXCITED BY RARE EARTH PERMANENT MAGNETS." Vestnik Chuvashskogo universiteta, no. 1 (March 25, 2021): 111–21. http://dx.doi.org/10.47026/1810-1909-2021-1-111-121.

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The article is devoted to improving the energy and performance characteristics of superminiature electric motors, which are widely used in modern devices of robotics and mechanotronics. With the development of digital and Autonomous robotic systems, the tasks of improving the efficiency of Executive micromechanisms that affect the functionality and duration of work in offline mode have become particularly relevant. Traditional design and technological solutions used in higher-power electric machines are not scalable to the field of superminiature electric machines. Domestic and foreign developers offer various design options and manufacturing technologies. The key design feature of the electric motor under consideration is a glass stator made by polycapillary fiber technology and an excitation system from rare-earth permanent magnets. In the wall of the glass case, holes are evenly distributed around the circumference, in which the control winding is laid. The motor excitation system is a two-pole permanent magnet located on the rotating rotor shaft. The purpose of the research is to determine the effect of changing the design of the excitation system by changing the location of the magnetic poles. The research uses software that simulates the electromagnetic field using the finite element method. In the course of research, it was found that a decrease in the body of a permanent magnet leads to a decrease in the electromagnetic moment, which is not compensated by a decrease in edge effects at the boundary of the poles of the magnet. However, an increase in the value of the maximum magnetic induction in the air gap allows us to conclude that edge effects at the pole boundary have a significant effect on reducing the energy characteristics of superminiature micromachines. Thus, the solutions proposed in this paper are not sufficient to increase the efficiency of the engine, but the data obtained indicate the need to reduce the edge effects of permanent magnets.

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Zhang, Desheng, Hongying Yang, and Qin Zhang. "Effect of Magnetic Stirring on Microstructures and Properties of Ag–1.5Cu–1.0Y Alloy." Materials 15, no. 15 (July 29, 2022): 5237. http://dx.doi.org/10.3390/ma15155237.

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The microstructure of alloys is an important factor that affects their application. In this work, the Ag–1.5Cu–1.0Y alloys were prepared by the permanent magnet stirring method at different rates. The secondary dendrite arm spacing, dendritic segregation, density, microhardness, electrical resistivity, and sulfuration corrosion resistance were analyzed to investigate the effects of different rotation speeds on the microstructures and properties of the Ag–1.5Cu–1.0Y alloy. The results showed that the primary dendrite was refined and the secondary dendrite arm spacing decreased with the increase in the stirring rate of the permanent magnets. The Ag–1.5Cu–1.0Y alloys prepared with a 900 r/min stirring rate had the largest microhardness, relatively high density, and the best sulfuration corrosion resistance. However, the stirring rate had little effect on the electrical resistivity of the Ag–1.5Cu–1.0Y alloys. To sum up, the Ag–1.5Cu–1.0Y alloy had the best comprehensive properties when the permanent magnet stirring rate was 900 r/min, including the most refined dendrites, relatively high density, the largest microhardness, and the best sulfuration corrosion resistance. The study of the effects of permanent magnet stirring speed on the microstructures and properties of the Ag–1.5Cu–1.0Y alloy provides an experimental basis for future alloy casting optimization and property improvement of silver-based alloys.

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37

Bifulco, Robert, Casey D. Cobb, and Courtney Bell. "Can Interdistrict Choice Boost Student Achievement? The Case of Connecticut’s Interdistrict Magnet School Program." Educational Evaluation and Policy Analysis 31, no. 4 (December 2009): 323–45. http://dx.doi.org/10.3102/0162373709340917.

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Connecticut’s interdistrict magnet schools offer a model of choice-based desegregation that appears to satisfy current legal constraints. This study presents evidence that interdistrict magnet schools have provided students from Connecticut’s central cities access to less racially and economically isolated educational environments and estimates the impact of attending a magnet school on student achievement. To address potential selection biases, the analyses exploit the random assignment that results from lottery-based admissions for a small set of schools, as well as value-added and fixed-effect estimators that rely on pre–magnet school measures of student achievement to obtain effect estimates for a broader set of interdistrict magnet schools. Results indicate that attendance at an interdistrict magnet high school has positive effects on the math and reading achievement of central city students and that interdistrict magnet middle schools have positive effects on reading achievement.

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38

Rahman, B. S., and D. K. Lieu. "The Origin of Permanent Magnet Induced Vibration in Electric Machines." Journal of Vibration and Acoustics 113, no. 4 (October 1, 1991): 476–81. http://dx.doi.org/10.1115/1.2930211.

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A principal source of vibration in permanent magnet motors and generators is the induced travelling forces from the rotating permanent magnets acting on the stator. The form of the magnetic field and resulting forcing function in the airgap of such machines is critical. The stator is modelled as a solid ring, with no teeth. Various motor parameters were investigated, including the effects of radial versus parallel magnetization, magnetization tolerances, and radial offset. The results were determined with analytical and FEM models. It was concluded that radial magnetization of the permanent magnets was preferable for both vibration and motor performance. Magnetization tolerances and radial offsets yielded a relatively more populated frequency spectrum for the forcing function and thus could lead to a greater probability of resonant modes being excited in the surrounding structure.

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39

Satoh, K., J. Ishii, K. Oka, and T. Satoh. "Effects of Surface Treatment for Thermoplastic Magnet." IEEE Translation Journal on Magnetics in Japan 1, no. 3 (June 1985): 387–88. http://dx.doi.org/10.1109/tjmj.1985.4548609.

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40

Sawan, Mohamed E., and Peter L. Walstrom. "Superconducting Magnet Radiation Effects in Fusion Reactors." Fusion Technology 10, no. 3P2A (November 1986): 741–46. http://dx.doi.org/10.13182/fst86-a24829.

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41

Pyrhonen, Juha, Vesa Ruuskanen, Janne Nerg, Jussi Puranen, and Hanne Jussila. "Permanent-Magnet Length Effects in AC Machines." IEEE Transactions on Magnetics 46, no. 10 (October 2010): 3783–89. http://dx.doi.org/10.1109/tmag.2010.2050002.

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42

Безверхний, А. И., О. В. Коплак, Р. А. Валеев, Д. В. Королев, В. П. Пискорский, and Р. Б. Моргунов. "Влияние текстуры на ширину доменов в спеченных магнитах (PrDy)(FeCo)B и (NdDy)(FeCo)B." Физика твердого тела 61, no. 11 (2019): 2084. http://dx.doi.org/10.21883/ftt.2019.11.48411.523.

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AbstractWe analyzed magnetic force microscopy images of the surface of samples cut parallel and perpendicular to the texture created by applying a field in the process of pressing a magnet. The distribution of the linear size (width) of the domains correlates with the distribution of the projection area of grains onto the shear plane in sintered (PrDy)(FeCo)B magnets with radial magnetization and in prismatic (NdDy)(FeCo)B magnets. The effects of grain size and direction of the axes of easy magnetization of grains on the width of the domains, as the main factors controlling the domain structure, are discussed.

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Qin, Wan Zhong, Jie He, and Jia Hong Meng. "Research on Composite Powder and Magnet Properties of Bonded NdFeB Magnets." Advanced Materials Research 535-537 (June 2012): 1314–18. http://dx.doi.org/10.4028/www.scientific.net/amr.535-537.1314.

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The injection molding of magnetic powder could cost-effectively mass-produce net shape magnets. The manufacture technology and properties testing method of composite powder and bonded NdFeB magnets from injection molding were described in detail. The effects of content of binder, additives and magnetic powder on the magnetic property, mechanical property and fluidity of injection molding magnets were investigated. Furthermore, the effect mechanism was revealed microcosmically. The injection molding bonded magnets were prepared by using the MQP-B rapidly quenching NdFeB magnetic powder and polyamide 12. The magnetic properties are: Br=0.539T, Hcb=345.37kA/m, Hci=681.02kA/m, and (BH)max=47.37kJ/m3.

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44

Zarate, Sergio, Gaizka Almandoz, Gaizka Ugalde, Javier Poza, and Ana Julia Escalada. "Effects of manufacturing tolerances of permanent magnets in fractional slot permanent magnet synchronous machines." Journal of Engineering 2019, no. 17 (June 1, 2019): 4060–64. http://dx.doi.org/10.1049/joe.2018.8199.

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45

Mohammadi, Simah, Hashem Rafii-Tabar, and Pezhman Sasanpour. "Contribution of the dipole–dipole interaction to targeting efficiency of magnetite nanoparticles inside the blood vessel: A computational modeling analysis with different magnet geometries." Physics of Fluids 34, no. 3 (March 2022): 033601. http://dx.doi.org/10.1063/5.0082882.

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The widespread use of magnetite nanoparticles inside the bloodstream for diagnostic and therapeutic purposes has made the influence of the interaction forces between these nanoparticles an important issue for predicting their behavior for improving the effectiveness of the protocols. Magnets with various geometries have been used in different biomedical applications, such as targeted drug delivery, to guide drugs carrying magnetite nanoparticles to specific areas. In this regard, using computational modeling, we have employed a multiphysics modeling approach using the particle tracing module in the COMSOL software environment to investigate the behavior of magnetite nanoparticles considering not only the magnetophoretic force, but also the dipole–dipole interaction forces between the nanoparticles. The effects of different geometries of magnets on the induced magnetic flux density and the laminar flow velocity inside the bloodstream were studied as well. The results of our study show that each geometry of the magnet induces different magnetic flux density profile and laminar velocity inside the blood flow. The behavior of ferrofluid flow is dependent on the geometry of the magnet and its remanent flux density. By increasing the size of magnetic nanoparticles, the magnetophoretic force enhances the particle velocity in the direction perpendicular to the vessel's walls, which could result in pull out. The results also reveal that the magnetic dipole–dipole interactions between nanoparticles could lead to the induction of higher dipole–dipole interaction forces in regions close to the magnet, especially on the upper wall of the blood vessel.

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46

Sumardi, Salman Farisi Rochmah Agustrina, and Yunita. "Effects of Magnetic Fields and Metal Ions (Cu, Pb, Al and Fe) on Growth of Anoxygenic Photosynthetic Bacteria (APB)." Biospecies 12, no. 2 (October 16, 2019): 42–50. http://dx.doi.org/10.22437/biospecies.v12i2.7595.

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Bakteri Fotosintetik Anoksigenik (BFA) memiliki sifat yang menguntungkan diantaranya sebagai kandidat probiotik, biofertilizer, agen bioremediasi dan mampu menurunkan konsetrasi H2S di perairan. Namun demikian BFA pun memiliki kelemahan yaitu pertumbuhannya lambat. Interaksi ion logam dan paparan medan magnet diketahui dapat meningkatkan aktivitas enzim dan meningkatkan laju pertumbuhan. Penelitian ini bertujuan untuk mengetahui pengaruh ion logam dan paparan medan magnet terhadap pertumbuhan BFA. Isolat BFA AM hasil isolasi dari akar mangrove diuji pengaruhnya terhadap ion logam dalam media sea water complete (SWC). Ion logam yang diujikan adalah Cu, Pb, Al dan Fe dengan konsentrasi yang berbeda. Ion logam dipapar medan magnet 0,2 mT selama 10 menit sebelum ditambahkan ke media. Hasil penghitungan sel menunjukkan bahwa ion logam baik yang dipapar medan magnet dan tanpa dipapar medan magnet tidak berpengaruh terhadap pertumbuhan isolat BFA AM, namun ion logam dalam media SWC mempengaruhi pola spektra isolat BFA AM.

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Li, Bing Bing, Yi Long Ma, Chun Hong Li, Xue Guo Yin, Qiang Zheng, Jian Chun Sun, Dong Ling Guo, Bin Shao, and Wen Zeng. "Effects of Co, Zr Additions on the Magnetic Properties of Nanocomposite Nd₂Fe₁₄B/α-Fe Magnets." Materials Science Forum 898 (June 2017): 2128–33. http://dx.doi.org/10.4028/www.scientific.net/msf.898.2128.

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The effects of the additions of Co, Zr on microstructure and magnetic properties were studied for hot-deformed (HD) nanocomposite Nd11.5Fe81.5-xNb1CoxB6 (x=0, 2, 4, 8) and Nd11.5Fe82.5-xZrxB6 (x=0, 1) magnets, respectively. The remanence of hot-pressed (HP) magnets increased with increasing Co content firstly, but decreased when Co content was more than 2 at. % for HD magnets. Also the intrinsic coercivity (Hci) and maximum energy product ((BH)m) of HD alloys increased firstly, and then decreased with further increasing Co content. The maximum (BH)m of 24 MGOe was obtained at 2 at.% Co addition. Zr addition can improve significantly the c-axis alignment and magnetic properties of HD nanocomposite magnets, and HD Nd11.5Fe81.5Zr1B6 magnet with 1.5 wt.% Zn addition showed enhanced properties with Hci of 7100 Oe and remanent magnetization (Mr) of 1.06 T. The alloys have the structure of plate-like grains, but there are still many coarse grains, which may result from the un-uniform composition in the alloy.

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Gaulin, Bruce. "Neutron and X-ray Diffraction from Exotic Magnets in Pulsed Magnetic Fields." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C149. http://dx.doi.org/10.1107/s2053273314098507.

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Magnetic fields obtained by discharging a large capacitor bank through Helmholtz coils can be produced in excess of 25 T for relatively short periods of time, ~ 1 msec and longer. When combined with modern facilities for diffraction at modern neutron and synchrotron x-ray sources, one can study the structure and phase diagrams of new materials under extremes of magnetic field. I will present two such studies, each focussing on a new magnetic material which exhibit exotic low temperature states. I will show time-resolved neutron Laue diffraction on the multiferroic magnet MnWO4 [1], and time-resolved synchrotron x-ray studies of large magneto-elastic effects in the geometrically-frustarted pyrochlore magnet Tb2Ti2O7 [2], both in magnetic fields up to ~ 30 T. Such studies of new materials in extreme sample environments can be very revealing as to the nature of their exotic low temperature states.

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49

Qiu, Hongbo, Wenfei Yu, Bingxia Tang, Weili Li, Cunxiang Yang, and Yanfeng Wang. "Effects of driving modes on permanent magnet motor electromagnetic and temperature fields at limit conditions." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 35, no. 6 (November 7, 2016): 2045–62. http://dx.doi.org/10.1108/compel-04-2016-0148.

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Purpose Taking a 2,000 r/min 10 kW permanent magnet motor as an example, the purpose of this paper is to study the influence of driving modes on the performance of permanent magnet motor at limit conditions, and researched the variation mechanism of motor performance influenced by different driving modes. Design/methodology/approach A two-dimensional electromagnetic field model of the permanent magnet motor was established, and a rectangular-wave driving circuit was built. By using the finite element method, the electromagnetic field, current, harmonic content and eddy current loss were calculated when the motor operated at rated load and limit load. On the basis of the motor loss calculation, the temperature field of the motor operating at rated condition and limit condition was researched, and the factors that influence motor limit overload capacity were analyzed. By analyzing the motor loss variation at different load conditions, the change mechanism of the motor temperature field was determined further. Combined with the related experiments, the correctness of the above analysis was verified. Findings Permanent magnet synchronous motor (PMSM) driven by sine wave is better compared with brushless direct current motor (BLDCM) driven by rectangular wave in reducing the magnetic field harmonics, motor losses and optimizing the temperature distribution in the motor. The method driven by sine wave could improve the motor output performance including the motor efficiency and the motor overload capacity. The winding temperature is the most important factor that limits the output capability of PMSM operating for a long time. However, because of the large rotor eddy current losses, the permanent magnet temperature is the most important factor that limits the output capability of BLDCM operating for a long time. Practical implications The influence of driving modes on the motor magnetic field, losses and temperature distribution, efficiency and overload capacity was determined, and the influence mechanism was also analyzed. Combined with the analysis of the electromagnetic and temperature fields, the advantages of different driving modes were presented. This study could provide an important basis for the design of permanent magnet motors with different driving modes, and it also provides reference for the application of permanent magnet motor. Originality/value This paper presents the influence of driving modes on permanent magnet motors. The limit output capacity of the motor with different driving modes was studied, and the key factors limiting the motor output capability were obtained.

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Jia, Feng-Ming, Jiao-Xu Mei, Rui-Feng Wang, Gang Cheng, Kun Liu, and Xiao-Ming Gao. "Optimization of distribution of permanent magnetrings for Faraday rotation spectroscopy." Acta Physica Sinica 71, no. 8 (2022): 080701. http://dx.doi.org/10.7498/aps.71.20212031.

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Faraday rotation spectroscopy (FRS) is generally used to detect the concentrations of various paramagnetic trace gases because of its high detection sensitivity, zero background noise and the ability to get rid of the interference of diamagnetic materials effectively. In most of FRS technologies, the used electromagnetic fields are produced by AC coils, thereby triggering off some problems such as high energy consumption and excessive heat generation. Thus the modeling and the simulation study of spatial magnetic field distribution based on the combined ring permanent magnets are carried out to establish an axially distributed homogeneous magnetic field and provide a permanent magnet-based homogeneous magnetic field along the optical axis for FRS measurement. In this simulation, the method of finite element mesh division is adopted based on basic electromagnetic relationship in Maxwell equations. By the simulation study of the magnetic field distribution of the actual Nd-Fe-B permanent magnet magnetic ring array, the physical model proves to be reliable. Basically, three methods of optimizing the permanent magnetic ring arrays. i.e. single ideal value optimization method, the multi-part single objective optimization method, and the gradient optimization method, are proposed. The single ideal value optimization method and the multiple ideal value optimization method are used to realize the optimization of magnets. However, by analyzing the two methods, it is clear that compared with the single ideal value optimization method, the multiple ideal value optimization method in which the whole region is divided into several small parts can achieve good uniformity of permanent magnet array. In this way, the third method, i.e. the gradient optimization method is used to realize the construction of a homogeneous magnetic field with a uniform central axis magnetic flux density distribution used for FRS. Finally, the standard magnetic field uniformity for measuring the quality of magnet field is suggested, and through the calculation and evaluation of the magnetic field uniformity, the optimization effects of different optimization methods are analyzed and compared with each other. And the final results about realizing a homogeneous magnetic field provide a reference for developing the FRS equipment based on permanent magnets.

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Journal articles on the topic 'Magnet effects'

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