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Journal articles on the topic 'Magnets'
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1
Dong, S. X., B. Li, B. S. Zhang, X. Q. Wang, and G. Y. Feng. "Design of A Permanent Quadrupole Magnet with Adjustable Magnetic Field Gradient." Journal of Physics: Conference Series 2687, no. 2 (January 1, 2024): 022029. http://dx.doi.org/10.1088/1742-6596/2687/2/022029.
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Abstract As compared to traditional magnets, permanent magnets can effectively reduce energy consumption and eliminate the impact of current ripple and the water cooling system on beam current. The use of permanent magnets in accelerators has become a new trend as permanent magnet technology has advanced. In HALF (Hefei Advanced Light Facility), we have designed a permanent magnet based on the quadrupole magnet, and the central magnetic field strength of the permanent magnet can be adjusted, indicating that single or multiple permanent magnets can be developed to replace different sizes of quadrupole magnets in accelerators, greatly improving systematization. The magnet’s mechanical design has been finalized, and the prototype of the permanent magnet will be manufactured and tested soon.
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Nagai, Keita, Naohiro Sugita, and Tadahiko Shinshi. "Batch Fine Magnetic Pattern Transfer Method on Permanent Magnets Using Coercivity Change during Heating for Magnetic MEMS." Micromachines 15, no. 2 (February 7, 2024): 248. http://dx.doi.org/10.3390/mi15020248.
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In magnetic microelectromechanical systems (MEMSs), permanent magnets in the form of a thick film or thin plate are used for structural and manufacturing purposes. However, the geometric shape induces a strong self-demagnetization field during thickness–direction magnetization, limiting the surface magnetic flux density and output power. The magnets must be segmented or magnetized in a fine and multi-pole manner to weaken the self-demagnetization field. Few studies have been performed on fine multi-pole magnetization techniques that can generate a higher surface magnetic flux density than segmented magnets and are suitable for mass production. This paper proposes a batch fine multi-pole magnetic pattern transfer (MPT) method for the magnets of MEMS devices. The proposed method uses two master magnets with identical magnetic patterns to sandwich a target magnet. Subsequently, the coercivity of the target magnet is reduced via heating, and the master magnet’s magnetic pattern is transferred to the target magnet. Stripe, checkerboard, and concentric circle patterns with a pole pitch of 0.3 mm are magnetized on the NdFeB master magnets N38EH with high intrinsic coercivity via laser-assisted heating magnetization. The MPT yields the highest surface magnetic flux density at 160 °C, reaching 39.7–66.1% of the ideal magnetization pattern on the NdFeB target magnet N35.
3
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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Kaňuch, Ján, and Želmíra Ferková. "Design and simulation of disk stepper motor with permanent magnets." Archives of Electrical Engineering 62, no. 2 (June 1, 2013): 281–88. http://dx.doi.org/10.2478/aee-2013-0022.
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Abstract In this paper the design and the magneto-static simulation of axial-flux permanent- magnet stepper motor with the disc type rotor is presented. Disk motors are particularly suitable for electrical vehicles, robots, valve control, pumps, centrifuges, fans, machine tools and manufacturing. The brushless machine with axial flux and permanent magnets, also called the disc-type machine, is an interesting alternative to its cylindrical radial flux counterpart due to the disk shape, compact construction and high torque density. This paper describes a design of four phase microstepping motor with the disc type rotor. The FEM modeling and the 3D magneto-static simulation of the disk stepper motor with permanent magnets is being subject of the article, too. Disc rotor type permanent magnet stepper motor for high torque to inertia ratio is ideal for robotics and CNC machines.
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Zhang, Yuyang, Yonggang Leng, Hao Zhang, Xukun Su, Shuailing Sun, Xiaoyu Chen, and Junjie Xu. "Comparative study on equivalent models calculating magnetic force between permanent magnets." Journal of Intelligent Manufacturing and Special Equipment 1, no. 1 (November 18, 2020): 43–65. http://dx.doi.org/10.1108/jimse-09-2020-0009.
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PurposeAn appropriate equivalent model is the key to the effective analysis of the system and structure in which permanent magnet takes part. At present, there are several equivalent models for calculating the interacting magnetic force between permanent magnets including magnetizing current, magnetic charge and magnetic dipole–dipole model. How to choose the most appropriate and efficient model still needs further discussion.Design/methodology/approachThis paper chooses cuboid, cylindrical and spherical permanent magnets as calculating objects to investigate the detailed calculation procedures based on three equivalent models, magnetizing current, magnetic charge and magnetic dipole–dipole model. By comparing the accuracies of those models with experiment measurement, the applicability of three equivalent models for describing permanent magnets with different shapes is analyzed.FindingsSimilar calculation accuracies of the equivalent magnetizing current model and magnetic charge model are verified by comparison between simulation and experiment results. However, the magnetic dipole–dipole model can only accurately calculate for spherical magnet instead of other nonellipsoid magnets, because dipole model cannot describe the specific characteristics of magnet's shape, only sphere can be treated as the topological form of a dipole, namely a filled dot.Originality/valueThis work provides reference basis for choosing a proper model to calculate magnetic force in the design of electromechanical structures with permanent magnets. The applicability of different equivalent models describing permanent magnets with different shapes is discussed and the equivalence between the models is also analyzed.
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Wang, Yichao, Peng Gao, Xuan Luo, and Houxiang Han. "Electro-Magnetic and Stress Analysis of a −400 T2/m High-Field Gradient Magnet with a Room-Temperature Bore Size of 200 mm." Applied Sciences 14, no. 5 (February 21, 2024): 1744. http://dx.doi.org/10.3390/app14051744.
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High-field-strength gradient superconducting magnets have been widely used in many fields. With advancements in technology, the demand for large-aperture magnets is gradually increasing, but there is relatively little research on the design and stress–strain of large-aperture gradient magnets. This article presents the design and analysis of a superconducting magnet characterized by a high field strength of 10 T, a strong gradient of −400 T2/m, and a large room-temperature bore of 200 mm. The aim of this project is to establish an experimental setup for the growth of Ga1−xInxSb crystals. The study starts with an overview of the development process and applied research related to strong-gradient magnets. The study employs a magneto–electric force coupling method based on generalized stretching to theoretically optimize the gradient coil pre-stress parameters through orthogonalization parameter scanning. In addition, an analysis of the stress distribution in both the magnet coil and the mandrel is carried out. The results indicate that the stress and strain values for both the gradient coils and the frame are within the allowable range of their respective materials. The magnets can be designed to operate stably in theory. This article may provide a reference for designers in related fields in optimizing the design and stress–strain analysis of large, strong-gradient magnets.
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Mills, Allan. "William Gilbert and ‘Magnetization by Percussion’." Notes and Records of the Royal Society 65, no. 4 (June 2011): 411–16. http://dx.doi.org/10.1098/rsnr.2011.0014.
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In his De Magnete William Gilbert claims that it is possible to make a magnet by hammering a red-hot bar of wrought iron arranged north–south on an anvil. This is contrary to modern ideas concerning the ‘Curie temperature’ (770°C for carbon steel), and to the recognized susceptibility of steel magnets to mechanical abuse. It has proved impossible to replicate Gilbert's technique experimentally. Only lengthy cold hammering of hardened carbon steel specimens on a large ferrous anvil produced weak permanent magnets.
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Sun, R. X., Z. G. Deng, Y. F. Gou, Y. J. Li, J. Zheng, S. Y. Wang, and J. S. Wang. "Feasibility of low-cost magnetic rail designs by integrating ferrite magnets and NdFeB magnets for HTS Maglev systems." International Journal of Modern Physics B 29, no. 25n26 (October 14, 2015): 1542043. http://dx.doi.org/10.1142/s0217979215420436.
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Permanent magnet guideway (PMG) is an indispensable part of high temperature superconducting (HTS) Maglev systems. Present PMGs are made of NdFeB magnets with excellent performance and cost much. As another permanent magnet material, the ferrite magnet is weak at magnetic energy product and coercive force, but inexpensive. So, it is a possible way to integrate the ferrite and NdFeB magnets for cutting down the cost of present PMGs. In the paper, the equivalent on magnetic field intensity between ferrite magnets and NdFeB magnets was evaluated by finite element simulation. According to the calculation results, the magnetic field of the PMG integrating ferrite magnets and NdFeB magnets can be increased remarkably comparing with the pure ferrite PMG. It indicates that low-cost PMG designs by integrating the two permanent magnet materials are feasible for the practical HTS Maglev system.
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Chang, Sungwoo, Noboru Niguchi, Je-Hoon Lee, and Katsuhiro Hirata. "Improvement of Torque Performance and Energy Density of PM-Type Vernier Motor Utilizing Saddle Coil and Salient Pole." Applied Sciences 11, no. 6 (March 22, 2021): 2818. http://dx.doi.org/10.3390/app11062818.
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In electric motors, the use of rare-earth magnets has been increasing rapidly. A stronger magnet force of the magnet enables the motor’s higher performance, resulting in the most high-performance motors generally using rare-earth magnets. However, these magnets have two crucial disadvantages: the potential restrictions on the supply of rare-earth magnetic materials and the sharp fluctuation in price. Thus, many recent researches focus on developing high-performance electric motors and reducing the use of critical rare-earth magnets. By increasing the torque density of the motor, we can reduce the use of permanent magnets. Focusing on this point, and we presented a double half permanent magnet (DHPM)-type vernier motor. This paper proposed a new saddle coil permanent magnet vernier motor with improved performance compared to its predecessor. The main feature of the proposed motor is that the permanent magnet and coil in the stator of a DHPM-type vernier motor is replaced by salient poles and saddle coils, respectively. We also investigate its characteristics through various simulations.
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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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Yun, James M., Michelle W. Colburn, and Patrick J. Antonelli. "Cochlear Implant Magnet Displacement With Minor Head Trauma." Otolaryngology–Head and Neck Surgery 133, no. 2 (August 2005): 275–77. http://dx.doi.org/10.1016/j.otohns.2005.02.018.
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Objectives: Manufacturers have introduced cochlear implants (CIs) with removable magnets to allow for magnetic resonance imaging after placement. The purpose of this study was to describe magnet displacement as a new CI complication and to suggest apossible treatment option to prevent its recurrence. Study Design: Retrospective case series. Methods: The records of 3 young males who experienced CI magnet dislodgement were reviewed and compared against records from the institutional implant database. Results: Magnet displacement was observed only in young males (14% of male children) who received CI with removable magnets. This occurred 13-14 months after CI placement. Magnets were replaced under general anesthesia, and the scalp was bolstered with a dermal allograft. Recurrent magnet dislodgement was encountered in 1 patient, 6 months later. Conclusions: Magnet displacement may be a relatively common complication after minor head trauma in pediatric patients with certain CIs that have removable magnets.
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Yang, Mei, Fusan Chen, Xianjing Sun, Zhuo Zhang, Wen Kang, and Yingshun Zhu. "Development of the CEPC collider prototype magnets." International Journal of Modern Physics A 36, no. 22 (July 28, 2021): 2142009. http://dx.doi.org/10.1142/s0217751x21420094.
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A Circular Electron Positron Collider (CEPC) with a circumference of about 100 km and a beam energy up to 120 GeV is proposed to be constructed in China. Over 80% of the collider ring is covered by conventional magnets. Most dipole and quadrupole magnets are twin aperture magnets with an inter-beam separation of 350 mm. Two 1-meter-long twin aperture prototype magnets are designed and manufactured. One is a combined dipole–sextupole magnet with aluminum bus bar coils, and the other one is a twin aperture quadrupole magnet with a DT4 compensation sheet to reduce the crosstalk effect between the two apertures. The design, fabrication and magnetic measurement of two prototype magnets are described in this paper.
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Prokofev, Pavel A., Natalia B. Kolchugina, Katerina Skotnicova, Gennady S. Burkhanov, Miroslav Kursa, Mark V. Zheleznyi, Nikolay A. Dormidontov, et al. "Blending Powder Process for Recycling Sintered Nd-Fe-B Magnets." Materials 13, no. 14 (July 8, 2020): 3049. http://dx.doi.org/10.3390/ma13143049.
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The wide application of Nd-Fe-B permanent magnets, in addition to rare-earth metal resource constraints, creates the necessity of the development of efficient technologies for recycling sintered Nd-Fe-B permanent magnets. In the present study, a magnet-to-magnet recycling process is considered. As starting materials, magnets of different grades were used, which were processed by hydrogen decrepitation and blending the powder with NdHx. Composition inhomogeneity in the Nd2Fe14B-based magnetic phase grains in the recycled magnets and the existence of a core-shell structure consisting of a Nd-rich (Dy-depleted) core and Nd-depleted (Dy-enriched) shell are demonstrated. The formation of this structure results from the grain boundary diffusion process of Dy that occurs during the sintering of magnets prepared from a mixture of Dy-free (N42) and Dy-containing magnets. The increase in the coercive force of the N42 magnet was shown to be 52%. The simultaneous retention of the remanence, and even its increase, were observed and explained by the improved isolation of the main magnetic phase grains as well as their alignment.
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Kriswanto, Rizqi Fitri Nuryanto, Renaldy Prasdiansyah, Dony Hidayat Al-Janan, Widya Aryadi, Ahmad Roziqin, Samsudin Anis, Wirawan Sumbodo, and Jamari. "Analysis of an Axial Permanent Magnetic Bearing for 1MW Horizontal Axis Wind." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 94, no. 1 (April 19, 2022): 172–87. http://dx.doi.org/10.37934/arfmts.94.1.172187.
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One way to reduce maintenance costs while improving wind turbine efficiency is to replace mechanical bearings with permanent magnetic bearings. The permanent magnetic bearing is a free contact bearing in which the rotor is elevated from the stator by the magnet's repelling force. The purpose of this study is to analyze the variation of permanent magnet width and the gap distance between the rotor-stator magnets that can produce the magnetic axial force opposing the thrust force of 1MW horizontal axis wind turbines (HAWT). The method used in this study is a magnetic force simulation using finite element method by varying the magnet thickness, width of the gap, and displacement between the rotor-stator of the PMB model. The PMB model consists of rotor and stator magnets arranged in 3 layers with Nd2Fe14B type material with a magnetic flux density of 1.45 T. Variations in thickness of the rotor and stator magnets are 0.1; 0.15, respectively; 0.2 (m), while variations in the width of the magnetic gap are 4, 5, 6 (mm). The results of the study found that the displacement that produces an axial magnetic force that can support a thrust force of 199.5kN is the lowest in the PMB model with a magnetic thickness of 0.15m with a magnetic gap of 4mm, while the highest is at a magnetic thickness of 0.1m with a magnet gap of 6mm. The greater the thickness of the PMB axial magnet design, the greater the displacement that provides zero axial magnetic forces. Further, the maximum of the magnetic axial force is rise on with increasing magnet thickness.
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Sandler, P. J., S. Meghji, A. M. Murray, S. D. Springate, J. R. Sandy, V. Crow, and R. T. Reed. "Magnets and Orthodontics." British Journal of Orthodontics 16, no. 4 (November 1989): 243–49. http://dx.doi.org/10.1179/bjo.16.4.243.
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The first part of this paper is a literature review of magnets and their uses in orthodontics. The biological safety of magnets is considered and a report is given of experiments carried out on rat osteosarcoma cell line UMR-106. The second part of the paper describes a case where neodynium-iron-boron magnets were used to assist eruption of an unerupted, vertically impacted upper right canine. Previously, space was available for this tooth, but it failed to show signs of eruption. Following surgical attachment of a magnet, and the use of a second magnet attached to an upper removable appliance, rapid eruption occurred producing a favourable position for bonding.
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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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Hodges, Nichole L., Sarah A. Denny, and Gary A. Smith. "Rare-Earth Magnet Ingestion–Related Injuries in the Pediatric Population: A Review." American Journal of Lifestyle Medicine 11, no. 3 (July 22, 2015): 259–63. http://dx.doi.org/10.1177/1559827615594336.
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Foreign-body ingestions are common among children and usually resolve with limited, if any, treatment. The ingestion of rare-earth magnets, however, commonly results in serious injury or death. These dangerous high-powered magnets can be found in the United States in a variety of consumer products, including magnetic toy sets designed for children and adults. The ingestion of one of such magnet is unlikely to cause significant harm. However, if multiple magnets are ingested, or if a magnet is ingested along with a metal object, the magnets are powerful enough to attract each other through the walls of the intestine, potentially resulting in significant internal damage. Rare-earth magnet ingestion cases are difficult to diagnose and the symptoms are not easy to differentiate from other causes of gastrointestinal illness or pain. However, delays in medical treatment can lead to serious injury or death. This review article describes the epidemiology of rare-earth magnet ingestion-related injuries and provides recommendations for diagnosis and treatment. Federal regulatory efforts related to rare-earth magnets and other prevention strategies are also discussed.
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Imashuku, Susumu, Kazuaki Wagatsuma, and Jun Kawai. "Scanning Electron Microscope-Cathodoluminescence Analysis of Rare-Earth Elements in Magnets." Microscopy and Microanalysis 22, no. 1 (January 7, 2016): 82–86. http://dx.doi.org/10.1017/s1431927615015676.
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AbstractScanning electron microscope-cathodoluminescence (SEM-CL) analysis was performed for neodymium–iron–boron (NdFeB) and samarium–cobalt (Sm–Co) magnets to analyze the rare-earth elements present in the magnets. We examined the advantages of SEM-CL analysis over conventional analytical methods such as SEM-energy-dispersive X-ray (EDX) spectroscopy and SEM-wavelength-dispersive X-ray (WDX) spectroscopy for elemental analysis of rare-earth elements in NdFeB magnets. Luminescence spectra of chloride compounds of elements in the magnets were measured by the SEM-CL method. Chloride compounds were obtained by the dropwise addition of hydrochloric acid on the magnets followed by drying in vacuum. Neodymium, praseodymium, terbium, and dysprosium were separately detected in the NdFeB magnets, and samarium was detected in the Sm–Co magnet by the SEM-CL method. In contrast, it was difficult to distinguish terbium and dysprosium in the NdFeB magnet with a dysprosium concentration of 1.05 wt% by conventional SEM-EDX analysis. Terbium with a concentration of 0.02 wt% in an NdFeB magnet was detected by SEM-CL analysis, but not by conventional SEM-WDX analysis. SEM-CL analysis is advantageous over conventional SEM-EDX and SEM-WDX analyses for detecting trace rare-earth elements in NdFeB magnets, particularly dysprosium and terbium.
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Zhu, Caoxiang, Kenneth Hammond, Adam Rutkowski, Keith Corrigan, Douglas Bishop, Arthur Brooks, Peter Dugan, et al. "PM4Stell: A prototype permanent magnet stellarator structure." Physics of Plasmas 29, no. 11 (November 2022): 112501. http://dx.doi.org/10.1063/5.0102754.
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Permanent magnets provide a possible solution to simplify complicated stellarator coils. A prototype permanent magnet stellarator structure, PM4Stell, has been funded to demonstrate the technical feasibility of using permanent magnets to create the shaping field of a stellarator. Permanent magnets in uniform cubes with three polarization directions will be carefully placed to generate the required magnetic field for a National Compact Stellarator eXperiment-like equilibrium together with planar toroidal field coils. Discrete magnets will be glued together and inserted into a “post-office-box-like” supporting structure. Electromagnetic and structural analyses have been done to validate the design. Error field correction magnets will be used to shim possible error fields. The design efforts of the prototype permanent magnet stellarator structure are discussed.
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Pangkung, Andareas, A. M. Shiddiq Yunus, Mustari Nur Mulyadi, and Padidi Alfrianto Illa. "Rancang Bangun Alternator Mobil Menggunakan Magnet Permanen." Jurnal Teknik Mesin Sinergi 19, no. 2 (November 22, 2021): 163. http://dx.doi.org/10.31963/sinergi.v19i2.3021.
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The electric power system is one of the sources of electricity found in the vehicle which functions as a starter and electric component of the vehicle. The battery (battery) is a source of electricity to meet the electrical system in the car, but the battery is only a place to store electric charge. Therefore, there is an alternator as a power generator to charge the battery. The alternator on a car uses artificial magnets in its rotor which still require excitation. Therefore, it encourages the author to analyze the comparison of alternators using permanent magnets and artificial magnets. The problem that arises is how to compare rotation, voltage, and output power on the alternator using permanent magnets and artificial magnets. The purpose of this study was to determine the ratio of the output power generated by the alternator using permanent magnets and artificial magnets. Research and Development Methods are research methods used to produce certain products, and test the effectiveness of these products. Based on the results of the tests carried out, it was found that at the same rotation an alternator with a permanent magnet generates a greater output power than the artificial magnet. However, at the same rotation the motor requires more input power to rotate the alternator when using permanent magnets. When the alternator output voltage is the same, the rotation of the alternator using the permanent magnet is lower.
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Bandeira, M. C. E., F. D. Prochnow, Isolda Costa, and César V. Franco. "Corrosion Resistance of Nd-Fe-B Magnets Coated with Polypyrrole Films." Materials Science Forum 530-531 (November 2006): 111–16. http://dx.doi.org/10.4028/www.scientific.net/msf.530-531.111.
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Nd-Fe-B magnets present outstanding magnetic properties. However, due to their low corrosion resistance, their applications are limited to non-corrosive environments. Nowadays, significant efforts are underway to increase the corrosion resistance of these materials, through the use of coatings. Herein are presented the results of a study on the corrosion resistance of Nd-Fe-B magnets coated with polypyrrole (PPY). The electrochemical behavior of coated and uncoated magnets has been studied by Electrochemical Impedance spectroscopy (EIS) in synthetic saliva. The results were compared to previous investigations, which were carried out under similar conditions, in Na2SO4 and NaCl solutions. In sulphate solution, the corrosion resistance of the PPY-coated magnet was 3 times larger (1600 .cm2) than that of uncoated magnet (500 .cm2). In NaCl solution, however, the corrosion resistance of coated and uncoated magnets were very similar (250 .cm2). In synthetic saliva, both the uncoated and coated magnets presented good corrosion performance (1940 .cm2). Such behavior can be attributed to the phosphate ions in saliva, which play a role as corrosion inhibitor, producing phosphating, at least partially, of the magnet surface. The PPY-coated magnets presented a strong diffusional control from moderate to low frequencies, caused by the polypyrrole film. The thicker PPY film increased the corrosion resistance of the magnet in synthetic saliva.
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Hunkun, Jiao, and Oleg Avrunin. "Feasibility analysis of implant movement along arc trajectory under non-contact control in magnetic stereotaxic system." Innovative Technologies and Scientific Solutions for Industries, no. 3(25) (September 30, 2023): 174–82. http://dx.doi.org/10.30837/itssi.2023.25.174.
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In this paper, the non-contact control of magnetic implants by changing the external magnetic field in the magnetic stereotaxic system is introduced, and the feasibility of making them move along the arc trajectory is analyzed. Through COMSOL software, the process of moving the miniature magnetic implant along the arc trajectory was simulated, the change of the micro-magnetic implant trajectory after the external magnetic field was changed, the relative position relationship between the large permanent magnets was determined, and the mechanical analysis of the miniature magnetic implant moving along the arc trajectory was carried out. In this experiment, we fix a large permanent magnet, only move the second permanent magnet, first, observe the process of small permanent magnets moving along a straight trajectory, determine the position of the large permanent magnet magnetic field when it contacts the small permanent magnet, and then, analyze the force of the small permanent magnet through the force calculation module, and determine the relative position relationship between the two large permanent magnets by comparing and , and when the small permanent magnet will start to move along the arc trajectory. Then, according to the previous data, we move two adjacent large permanent magnets at the same time at a certain interval, record the movement trajectory of the small magnet, Finally, with the force calculation module of the COMSOL software, force analysis of small permanent magnets moving along arc trajectories. The data from this experiment will be used to determine the relative position relationship between two large permanent magnets adjacent to each other during the actual experiment, and under what conditions the small permanent magnets will move along the arc trajectory. The purpose of this experiment is to provide theoretical and data support for the subsequent practical experiments of the magnetic stereotactic system, and all parameters in the COMSOL software are derived from the actual measurement data, so as to improve the reliability of the simulation results.
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Zhu, Xin-De, Mei Wang, Yong-Jiang Yu, Qian Wang, Fei Wang, Peng-Fei Wang, Bin Jia, Cong Wang, and Bin Zhou. "Coercivity Enhancement of Sintered Nd-Pr-Fe-B Magnets by Cost-Effective Grain Boundary Diffusion of Dy/Tb Films." Crystals 13, no. 10 (October 19, 2023): 1516. http://dx.doi.org/10.3390/cryst13101516.
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High-performance sintered Nd-Pr-Fe-B magnets were successfully prepared by depositing Dy/Tb films on the surface using magnetron sputtering, which resulted in superior grain boundary diffusion (GBD) under heat treatments. The course of the diffusion was assessed using an electron probe microanalyzer (EPMA) and inductively coupled plasma (ICP). The magnetic properties and thermal stability of the magnets before and after diffusion were investigated. The results show that, mainly due to the increased and optimized Nd-Pr-rich phases and the formation of the (Nd,Pr,Dy/Tb)2Fe14B shell structure surrounding the (Nd,Pr)2Fe14B grains, the coercivity of the Dy- and Tb-diffused magnets was enhanced from 16.7 kOe to 24.8 kOe and 28.4 kOe, respectively, while the corresponding maximum energy product (BHmax) was 48.1 MGOe and 48.5 MGOe, respectively. The consumption of Dy/Tb in this work (0.35 wt% Dy in the Dy-diffused magnet and 0.42 wt% Tb in the Tb-diffused magnet) is much lower than that of previously reported magnets with comparable coercivity. Furthermore, Dy- or Tb-diffused magnets exhibit better thermal stability than that of the original magnet, owing to the better resistance to thermal disturbances of the magnets with optimized microstructure. This work can provide useful guidance for preparing Nd-Fe-B magnets with low cost and high performance.
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Panchal, T. H., A. N. Patel, and R. M. Patel. "Reduction of cogging torque of radial flux permanent magnet brushless DC motor by magnet shifting technique." Electrical Engineering & Electromechanics, no. 3 (May 30, 2022): 15–20. http://dx.doi.org/10.20998/2074-272x.2022.3.03.
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Introduction. In spite of many advantages of radial flux permanent magnet brushless DC motors it suffers from the distinct disadvantage of high cogging torque. The designer must emphasize to reduce the cogging torque during the design stage. This paper introduces magnet shifting technique to mitigate cogging torque of surface mounted radial flux brushless DC motor. Methodology. Initially 200 W, 1000 rpm surface mounted radial flux permanent magnet brushless DC motor is designed with symmetrical placement of permanent magnets with respect to each other on rotor core. Cogging torque profile of this initial motor is obtained by performing finite element modelling and analysis. Originality. This design has been improved by shifting the position of permanent magnets with respect to adjacent permanent magnets. The effect of magnet shifting on cogging torque has been analyzed by performing finite element analysis. Results. It has been examined that the peak to peak cogging torque is decreased from 1.1 N×m to 0.6 N×m with shifting of permanent magnets respectively.
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Offermann, Peter, and Kay Hameyer. "A polynomial chaos meta‐model for non‐linear stochastic magnet variations." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 32, no. 4 (July 5, 2013): 1211–18. http://dx.doi.org/10.1108/03321641311317031.
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PurposeDue to the production process, arc segment magnets with radial magnetization for surface‐mounted permanent‐magnet synchronous machines (PMSM) can exhibit a deviation from the intended ideal, radial directed magnetization. In such cases, the resulting air gap field may show spatial variations in angle and absolute value of the flux‐density. For this purpose, this paper aims to create and evaluate a stochastic magnet model.Design/methodology/approachIn this paper, a polynomial chaos meta‐model approach, extracted from a finite element model, is compared to a direct sampling approach. Both approaches are evaluated using Monte‐Carlo simulation for the calculation of the flux‐density above one sole magnet surface.FindingsThe used approach allows representing the flux‐density's variations in terms of the magnet's stochastic input variations, which is not possible with pure Monte‐Carlo simulation. Furthermore, the resulting polynomial‐chaos meta‐model can be used to accelerate the calculation of error probabilities for a given limit state function by a factor of ten.Research limitations/implicationsDue to epistemic uncertainty magnet variations are assumed to be purely Gaussian distributed.Originality/valueThe comparison of both approaches verifies the assumption that the polynomial chaos meta‐model of the magnets will be applicable for a complete machine simulation.
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Accardo, Antonella, Trentalessandro Costantino, and Ezio Spessa. "LCA of Recycled (NdDy)FeB Permanent Magnets through Hydrogen Decrepitation." Energies 17, no. 4 (February 15, 2024): 908. http://dx.doi.org/10.3390/en17040908.
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Compared to conventional fossil-fueled vehicles, electric vehicles offer several environmental benefits. However, even electric vehicles are not completely environmentally friendly because many of their parts are not recycled today. These parts, especially the magnets that power them, end up in landfills at the end of the vehicle’s life cycle. This study aims to evaluate the environmental impacts of recycled (NdDy)FeB permanent magnets obtained by means of a novel hydrogen-decrepitation-based, magnet-to-magnet recycling technique. The Life Cycle Assessment methodology was used to compare, on a like-to-like basis, recycled and virgin permanent magnets. The core data provided by an industry partner served as the foundation for modelling the recycling process. Three different functional units were investigated based on three parameters, namely the magnet mass, magnetization coercivity, and energy product. Results revealed that the recycled magnet outperformed the virgin magnet in most impact categories. In terms of carbon footprint, recycling permanent magnets through hydrogen decrepitation would allow for an 18─33% reduction with respect to their production from virgin materials, depending on the assumed functional unit.
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Turvani, Giovanna, Laura D’Alessandro, and Marco Vacca. "Physical Simulations of High Speed and Low Power NanoMagnet Logic Circuits." Journal of Low Power Electronics and Applications 8, no. 4 (October 8, 2018): 37. http://dx.doi.org/10.3390/jlpea8040037.
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Among all “beyond CMOS” solutions currently under investigation, nanomagnetic logic (NML) technology is considered to be one of the most promising. In this technology, nanoscale magnets are rectangularly shaped and are characterized by the intrinsic capability of enabling logic and memory functions in the same device. The design of logic architectures is accomplished by the use of a clocking mechanism that is needed to properly propagate information. Previous works demonstrated that the magneto-elastic effect can be exploited to implement the clocking mechanism by altering the magnetization of magnets. With this paper, we present a novel clocking mechanism enabling the independent control of each single nanodevice exploiting the magneto-elastic effect and enabling high-speed NML circuits. We prove the effectiveness of this approach by performing several micromagnetic simulations. We characterized a chain of nanomagnets in different conditions (e.g., different distance among cells, different electrical fields, and different magnet geometries). This solution improves NML, the reliability of circuits, the fabrication process, and the operating frequency of circuits while keeping the energy consumption at an extremely low level.
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Ma, Jun. "The Effect of the Horizontal Distance between the Permanent Magnets on the Levitation Force in Hybrid Magnetic Levitation System." Advanced Materials Research 750-752 (August 2013): 987–90. http://dx.doi.org/10.4028/www.scientific.net/amr.750-752.987.
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It has been investigated that the interaction force in hybrid magnetic levitation systems with a GdBCO bulk superconductor and a permanent magnet system and two permanent magnets (PM2) and two cubic permanent magnets (PM3) system in their coaxial configuration at liquid nitrogen temperature. A single-domain GdBCO sample is of 20mm and 10mm in thickness, the permanent magnet PM1 is of rectangular parallelepiped shape, the permanent magnets PM2 and PM3 are of cubic shape; the system placed on the middle of system and their coaxial configuration; It is found that the maximum levitation force decreases from 46.3N to 16.3N while the horizontal distance (Dpp) between the rectangle permanent magnet and two cubic permanent magnets (PM2) is increased from 0mm to 24mm and the horizontal distance (Dsp) between a GdBCO bulk superconductor and two cubic permanent magnets (PM3) is 0mm, The results indicate that the higher levitation force can be obtained by introducing PM-PM levitation system based on scientific and reasonable design of the hybrid magnetic levitation system, which is helpful for designing and constructing superconducting magnetic levitation systems.
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Song, Si-Woo, Hyun-Jo Pyo, Dong-Woo Nam, Ju Lee, and Won-Ho Kim. "Irreversible Demagnetization Improvement Process of Hybrid Traction Motors with Dy-Free Magnets." Machines 11, no. 1 (December 21, 2022): 4. http://dx.doi.org/10.3390/machines11010004.
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Permanent magnet synchronous motors (PMSMs), with their high power density, high efficiency, and thermal stability, are widely used nowadays. PMSM magnets are composed of rare earth elements. However, rare earth elements are subject to severe price fluctuations because of their limited availability and the monopoly of some countries. Therefore, extensive research on magnets devoid of rare earth elements has been conducted recently. Although a magnet devoid of rare earth elements has a high irreversible demagnetization rate at high temperatures owing to its low coercive force, an irreversible demagnetization improvement process is proposed in this paper to compensate for this disadvantage. This process analyzes the contribution of the magnet’s back EMF (electromotive force) using the flux linkage equation, which does not change with time. Next, the location of irreversible demagnetization is moved to a position with a low contribution to the back electromotive force. Consequently, even if irreversible demagnetization occurs at the same size, the irreversible demagnetization ratio is reduced. The proposed process can minimize irreversible demagnetization while maintaining performance.
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Anantha Krishna, G. L., and K. M. Sathish Kumar. "Evaluation of brake parameters in copper discs of various thicknesses and speeds using Neodymium – Iron – Boron Magnets." MATEC Web of Conferences 144 (2018): 01003. http://dx.doi.org/10.1051/matecconf/201814401003.
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Neodymium – Iron – Boron (NdFeB) permanent magnets of 12.5 mm thickness and 50 mm diameter are chosen for analyses because of their higher remanence and coercivity. Experimental analyses were carried out with Copper discs of thickness 4 mm, 6 mm and 8 mm at 2000 rpm, 3000 rpm, 4000 rpm and 5000 rpm. Experiments were conducted with three different positions of magnets such as 2 coaxial magnets, single magnet and single magnet with sudden application conditions. The brake parameters recorded are % speed reduction, deceleration and time taken. In 2 coaxial magnets condition, brake parameters are better in 6 mm thick disc. In single magnet condition, the brake parameters in 6 mm thick disc are found to be more consistent than 4 mm and 8 mm thick discs. In single magnet with sudden application condition, in 4 mm thick disc, the brake parameters are found better. During analysis, very high repulsion was experienced by magnet with 8 mm thick Copper disc at all the above mentioned speeds in single magnet with sudden application condition. For high speed train applications, single magnet condition with 6mm thick disc may be suitable. For high speed automotive applications, single magnet with sudden application condition with 4 mm thick disc may be suitable.
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Radwan-Pragłowska, Natalia, and Tomasz Węgiel. "Permanent Magnet Selections for AFPM Disc Generators." Energies 15, no. 20 (October 14, 2022): 7601. http://dx.doi.org/10.3390/en15207601.
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In this article, the field (FEM) and analytical analyses were used for the optimal selection of magnets material for the Axial Flux Permanent Magnet Generator (AFPMG), without building the prototype before. The tested generator is an axial flux machine which consists of a single stator and two rotor discs with Permanent Magnets (PM). Three-dimensional (3D) ANSYS Maxwell package was used for magnetostatic and transient field (FEM) simulations. Two types of PM were selected for the analysis: Ceramic (also known as “Ferrite”) magnets made from Strontium Ferrite powder and Neodymium Iron Boron magnets (NdFeB). The authors compared obtained electromotive forces (EMF) and generator powers for selected magnets materials, performed FFT analyses of voltages and currents and indicated the optimal solutions. In addition to the operational properties of the AFPMG, the magnet and manufacturing costs were compared.
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DING, XIAOFENG, and CHRIS MI. "MODELING OF EDDY CURRENT LOSS AND TEMPERATURE OF THE MAGNETS IN PERMANENT MAGNET MACHINES." Journal of Circuits, Systems and Computers 20, no. 07 (November 2011): 1287–301. http://dx.doi.org/10.1142/s021812661100789x.
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The eddy current loss in the magnets of permanent magnet (PM) motors in a hybrid electric vehicle (HEV) and plug-in HEV is usually not taken into consideration in traditional motor design and analysis. However, due to the high conductivity of the rare-earth magnet, neodymium-iron-boron (NdFeB), and slot/tooth harmonics, there is eddy current loss generated inside the magnets. This loss may not attribute very much to the efficiency of the motor, but the temperature-rise inside the magnets caused by this loss can lead to the unpredictable deterioration of the magnets, such as the degradation of performance and potential demagnetization. In addition, the output voltage of pulse-width-modulated (PWM) inverter contains abundant high frequency harmonics, which induce excessive loss in the magnets. The excessive heat in PM motor induced by the eddy current loss combined with other losses can degrade the performance of the machine. This paper presents the modeling and analysis of eddy current loss in surface-mounted-magnets PM synchronous motors (SPMSM) and interior-magnets PM synchronous motors (IPMSM), operated by PWM inverter supply. Analytical methods are implemented, in conjunction with time-stepped finite-element analysis (FEA) for the calculation of eddy current loss in the magnet. Based on the calculated losses in the machines, simplified analytical models are developed as thermal circuits with network of interconnected nodes, thermal resistances and heat sources representing the heat processes within the SPMSM and IPMSM, to predict the temperature of the magnets. The predicted machine temperatures are found to be consistent with the experimental measurement.
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Abad, V., J. Sagredo, and J. Gonzalez. "FEA Analysis and Optimization of Rotor Models in Permanent-Magnet Synchronous Motors fitted with Bonded Rare-Earth Magnets." Energies and Quality Journal 1 (June 2019): 19–24. http://dx.doi.org/10.24084/eqj19.212.
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The Toyota Prius MG2 electric motor and its upgrades, since its first appearance in 1997, are presented in this paper. This electric motor has an Interior Permanent Magnet (IPM) fitted with Rare Earth (RE) magnets, which presents clear advantages over the more widely used Induction Motors (IM). The principal advantage is its high power-density value that makes it a leader in the Electric Vehicles (EV) market. This technology, however, faces a problem, in so far as the global production of RE magnets is an exclusive monopoly of China, (motivating the United States and Japan, among others, to investigate alternative systems). In this paper, the proposal is to substitute the sintered magnet in current use by the bonded type of magnet. The use of bonded magnets permits curved geometric forms, reducing the use of dysprosium, one of the most controversial elements of sintered magnets. These materials are compared using Finite Element Analysis (FEA) in the design of various rotor models including the proposal of a model with bonded magnetic materials, with the advantages of curved magnets and a dual layer arrangement. The proposed rotor model yielded a considerably higher power density than the model developed by Toyota. Keywords PMSM, Finite Element Analysis, Rare Earth Magnets.
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Idayanti, Novrita, Azwar Manaf, and Dedi Dedi. "Magnet Nanokomposit Sebagai Magnet Permanen Masa Depan [Nanocomposite Magnets as Future Permanent Magnets]." Metalurgi 33, no. 1 (June 20, 2018): 1. http://dx.doi.org/10.14203/metalurgi.v33i1.433.
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Hioki, Keiko. "Development of High-Performance Hot-Deformed Neodymium–Iron–Boron Magnets without Heavy Rare-Earth Elements." Materials 16, no. 19 (October 6, 2023): 6581. http://dx.doi.org/10.3390/ma16196581.
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Neodymium–iron–boron magnet is an essential material for the traction motors of green vehicles because it exhibits the highest maximum energy product, (BH)max, out of all permanent-magnet materials. However, heavy rare-earth elements such as dysprosium and terbium, which are scarce resources, are added to these magnets to improve their heat resistance. To address this resource problem, considerable efforts have been made to reduce the composition of heavy rare-earth elements in these magnets without causing a significant reduction in coercivity. Hot-deformed Nd-Fe-B magnets are a category of Nd-Fe-B magnets where precious materials such as heavy rare-earth elements can be eliminated or reduced to maintain high coercivity owing to their fine microstructure. Although they are not often used for the fabrication of high-performance magnets due to their complicated production process and the difficulty in controlling their fine microstructure, after the rare-earth crisis in 2020, these magnets have begun to attract attention as a material that could increase coercivity when controlling their microstructures. This paper provides an overview of hot-deformed magnets and the efforts made to improve their properties by controlling their microstructures.
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Cheedket, Sampart, and Chitnarong Sirisathitkul. "Comparison of closed-form solutions to experimental magnetic force between two cylindrical magnets." EUREKA: Physics and Engineering, no. 4 (July 23, 2021): 141–46. http://dx.doi.org/10.21303/2461-4262.2021.001955.
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The force between permanent magnets implemented in many engineering devices remains an intriguing problem in basic physics. The variation of magnetic force with the distance x between a pair of magnets cannot usually be approximated as x-4 because of the dipole nature and geometry of magnets. In this work, the force between two identical cylindrical magnets is accurately described by a closed-form solution. The analytical model assumes that the magnets are uniformly magnetized along their length. The calculation, based on the magnetic field exerted by one magnet on the other along the direction of their orientation, shows a reduction in the magnetic force with the distance x and a dependence on the size parameters of magnets. To verify the equation, the experiment was set up by placing two cylindrical neodymium iron boron type magnets in a vertical tube. The repulsive force between the identical upper and lower magnets of 2.5 cm in diameter and 7.5 cm in length was measured from the weight on the top of the upper magnet. The resulting separation between the magnets was recorded as x. The forces measured at x=0.004-0.037 m differ from the values calculated using the analytic solution by -0.55 % to -13.60 %. The calculation also gives rise to a practical remnant magnetic field of 1.206 T. When x is much large than the equation of force is approximated as a simple form proportional to 1/x-4. The finding can be directly used in magnetic levitation as well as applied in calculating magnetic fields and forces in other systems incorporating permanent magnets.
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Huang, Jingbin, Min Huang, Fang Wang, Zhanyong Wang, and Jian Zhang. "Microstructure Optimization and Coercivity Enhancement of Sintered NdFeB Magnet by Grain Boundary Diffusion of Multicomponent Tb60Pr10Cu10Al10Zn10 Films." Materials 16, no. 8 (April 16, 2023): 3131. http://dx.doi.org/10.3390/ma16083131.
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The use of magnetron sputtering film as a diffusion source was recently achieved in the industrial production of important grain-boundary-diffusion magnets. In this paper, the multicomponent diffusion source film is explored to optimize the microstructure of NdFeB magnets and improve their magnetic properties. Multicomponent Tb60Pr10Cu10Al10Zn10 films of 10 μm in thickness and single Tb films of 10 μm in thickness were deposited on commercial NdFeB magnets’ surfaces by magnetron sputtering as diffusion sources for grain boundary diffusion. The effects of diffusion on the microstructure and magnetic properties of the magnets were investigated. The coercivity of multicomponent diffusion magnets and single Tb diffusion magnets increased from 11.54 kOe to 18.89 kOe and 17.80 kOe, respectively. The microstructure and element distribution of diffusion magnets were characterized by scanning electron microscope and transmission electron microscopy. The multicomponent diffusion facilitates the infiltration of Tb along grain boundaries, rather than entering the main phase, thereby improving the Tb diffusion utilization. Furthermore, compared to the Tb diffusion magnet, the thicker thin-grain boundary was observed in multicomponent diffusion magnets. This thicker thin-grain boundary can effectively serve as the impetus for the magnetic exchange/coupling between grains. Therefore, the multicomponent diffusion magnets have higher coercivity and remanence. The multicomponent diffusion source has an increased mixing entropy and decreased Gibbs free energy, and it therefore does not easily enter the main phase but is retained in the grain boundary, thus optimizing the microstructure of the diffusion magnet. Our results show that the multicomponent diffusion source is an effective route for fabricating diffusion magnets with high performance.
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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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Manh, Tien Ho, Dinh Bui Minh, Tu Pham Minh, and Vuong Dang Quoc. "Investigation of the Influence of Skewed Slots and Degmagnetization Effects to Line Start Permanent Magnet Assistance Synchronous Reluctance Motors." Engineering, Technology & Applied Science Research 13, no. 1 (February 1, 2023): 9807–11. http://dx.doi.org/10.48084/etasr.5307.
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A permanent magnet assistance synchronous reluctance motor can start directly with a net voltage or a power converter via a torque control method. However, this motor has usually a higher irreversible demagnetization level in comparison with interior permanent magnet motors, due to the fewer permanent magnets in rotor slots. In order to cope with this disadvantage, different arrangements of permanent magnets in the rotor of the line-start permanent magnet assistance synchronous reluctance motor are proposed in this paper. The V magnet shape taking skewed slots and demagnetization effect into account with the short circuit current are investigated by the finite element approach. The efficiency, torque, and output power of the proposed model have been also improved. Finally, the rotor with 3V layered magnets is prototyped to verify the efficiency of the proposed motor.
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Rao, Dantam, and Madhan Bagianathan. "Selection of Optimal Magnets for Traction Motors to Prevent Demagnetization." Machines 9, no. 6 (June 20, 2021): 124. http://dx.doi.org/10.3390/machines9060124.
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Currently, permanent-magnet-type traction motors drive most electric vehicles. However, the potential demagnetization of magnets in these motors limits the performance of an electric vehicle. It is well known that during severe duty, the magnets are demagnetized if they operate beyond a ‘knee point’ in the B(H) curve. We show herein that the classic knee point definition can degrade a magnet by up to 4 grades. To prevent consequent excessive loss in performance, this paper defines the knee point k as the point of intersection of the B(H) curve and a parallel line that limits the reduction in its residual flux density to 1%. We show that operating above such a knee point will not be demagnetizing the magnets. It will also prevent a magnet from degenerating to a lower grade. The flux density at such a knee point, termed demag flux density, characterizes the onset of demagnetization. It rightly reflects the value of a magnet, so can be used as a basis to price the magnets. Including such knee points in the purchase specifications also helps avoid the penalty of getting the performance of a low-grade magnet out of a high-grade magnet. It also facilitates an accurate demagnetization analysis of traction motors in the worst-case conditions.
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Majdani, Omid, Martin Leinung, Thomas Rau, Arash Akbarian, Martin Zimmerling, Minoo Lenarz, Thomas Lenarz, and Robert Labadie. "Demagnetization of Cochlear Implants and Temperature Changes in 3.0T MRI Environment." Otolaryngology–Head and Neck Surgery 139, no. 6 (December 2008): 833–39. http://dx.doi.org/10.1016/j.otohns.2008.07.026.
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Objective To investigate the level of demagnetization of the magnets and temperature changes in cochlear implants (Cis) in a 3.0 tesla (3.0T) MRI. Study Design Experimental. Subjects and Methods Demagnetization and remagnetization measurements were done on magnets for different types of CIs. Temperature of different body and electrode sides was measured in the MRI environment. Results Demagnetization of the magnets of the CI is dependent on the angle between the magnetic field of the CI magnet and the MRI. When this angle was greater than 80 degrees, relevant demagnetization occurred and sufficient remagnetization was not possible with the 3.0T MRI magnet. Maximum temperature rise was 0.5°C. Conclusions Patients carrying CIs with non-removable magnets should not enter a 3.0T MRI device in a routine clinical setup. Under special conditions (angle between the two magnets less than 80 degrees) imaging in a 3.0T MRI may be possible without harming the patient or the implant.
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Zeising, Samuel, Lu Chen, Angelika Thalmayer, Georg Fischer, and Jens Kirchner. "Towards Differential Static Magnetic Localization of Commercial Capsule Endoscopes: An Evaluation Using Different Ring and Cylindrical Magnets." Advances in Radio Science 20 (March 21, 2023): 105–12. http://dx.doi.org/10.5194/ars-20-105-2023.
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Abstract. Capsule endoscopy is a promising diagnostic tool for the entire gastrointestinal tract. Since a patient swallows the capsules, their size must be sufficiently small. The principal built-in components are cameras, silver-oxide batteries, light emitting diodes, and an antenna for transmitting the video. For diagnosis and treatment, the precise localization of the capsules for specific video frames is required. Recently, static magnetic localization of these capsules with an integrated permanent magnet showed promising results. However, in the state-of-the-art, relatively large magnets compared to the small capsules were used. Therefore, in this extended paper, the localization performance of a recently proposed optimized differential static magnetic localization method for different sized disc and ring magnets was evaluated. The ring magnets were designed for integration with the two batteries of commercial capsules. The magnets were evaluated in static and dynamic scenarios to evaluate the performance of the method in a patient's daily life. It was revealed that the mean position and orientation errors did not exceed 5 mm and 4∘, respectively, for all applied magnets except for the 1.5 and 3 mm long disc magnets. Moreover, the results indicated that the ferromagnetic batteries of capsule endoscopes increase the localization performance when they are centered within a diametrical ring magnet. Overall, it was revealed that the localization performance of the optimized differential method is significantly better than the state-of-the-art even when the magnet volume is significantly reduced compared to previous work. Therefore, it was concluded that 5 mm long disc magnet or a ring magnet are excellent candidates for integration into a commercial capsule for magnetic localization and yield the advantage of being passive magnetic sources.
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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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Wu, Yichao, Yong Li, Guixian Wang, Chaohui Zhang, and Jihong Pang. "Performance Evaluation of a High-Torque Permanent Magnet Brake at Operating Temperature Based on Magneto-Thermal Coupling Method." Actuators 12, no. 4 (March 30, 2023): 149. http://dx.doi.org/10.3390/act12040149.
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As the key component of a servo motor, the torque and temperature rise of the brake at the operating temperature affect the production quality of injection molding machines and other equipment. To achieve application of the brake and evaluate its performance at a high operating temperature, a high-torque permanent magnet brake with an axial disc structure is proposed. The permanent magnet consists of six small magnets instead of the traditional monolithic ring magnet. The key parameters of the coil are designed, and the magneto-thermal coupling method is established. The magneto-thermal coupling method considers the effect of temperature on material properties and feeds the temperature back to the electromagnetic field to correct the resistance, permeability, remanence and other coefficients. It then updates the heat source of the temperature field. The temperature rise is calculated iteratively between the electromagnetic field and the temperature field. The simulation results of the one-way method and the magneto-thermal coupling method are obtained and compared with the experimental results. The evaluation errors of the magneto-thermal coupling method for temperature and braking torque are 1.9% and 4.7% respectively, which are lower than the errors of the one-way method.
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da Silva, Melissa Rohrig Martins, R. G. T. Fim, S. C. Silva, Julio Cesar Serafim Casini, P. A. P. Wendhausen, and Hidetoshi Takiishi. "Influence of Alloying Elements Zr, Nb and Mo on the Microstructure and Magnetic Properties of Sintered Pr-Fe-Co-B Based Permanent Magnets." Materials Science Forum 930 (September 2018): 440–44. http://dx.doi.org/10.4028/www.scientific.net/msf.930.440.
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The addition of alloying elements on rare-earth permanent magnets is one of the methods used to improve the magnetic properties. This present work evaluates the influence of alloying elements such as Zr, Nb and Mo on the microstructure and magnetic properties of sintered Pr-FeCo-B based permanent magnets. The permanent magnets were produced by the conventional powder metallurgy route using powder obtained by hydrogen-decrepitation (HD) method from as cast alloys. In order to produce the magnet Pr16Fe66,9Co10,7B5,7Cu0,7 without alloying elements the mixture of alloys method was employed, mixing two compositions: Pr20Fe73B5Cu2 (33% w.t) and Pr14Fe64Co16B6 (67% w.t). With the purpose of evaluating the influence of the alloying elements, the Pr14Fe64Co16B6X0,1 (where X= Zr, Nb or Mo) (67% w.t) alloy was employed. The characterization of the alloys and the magnets was carried out using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS) and the magnetic properties were measured using a permeameter. The magnet without any additions presented the highest intrinsic coercivity (μ0iHc = 748 KA.m-1) while the magnet with Nb addition presented higher remanence (Br = 1,04 T). The magnet with Zr addition presented the highest maximum energy product (BHmáx = 144 KJ.m-3), and the magnet with Mo addition showed the highest squareness factor (SF = 0,73).
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Bernad, Sandor I., and Elena Bernad. "Magnetic Forces by Permanent Magnets to Manipulate Magnetoresponsive Particles in Drug-Targeting Applications." Micromachines 13, no. 11 (October 25, 2022): 1818. http://dx.doi.org/10.3390/mi13111818.
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This study presents preliminary computational and experimental findings on two alternative permanent magnet configurations helpful for magnetic drug administration in vivo. A numerical simulation and a direct experimental measurement of the magnetic induction on the magnet system’s surface were used to map the magnetic field. In addition, the ferrite-type (grade Y35) and permanent neodymium magnets (grade N52) to produce powerful magnetic forces were also examined analytically and quantitatively. Ansys-Maxwell software and Finite Element Method Magnetism (FEMM) version 4.2 were used for all numerical computations in the current investigation. For both magnets, the generated magnetic fields were comparatively studied for targeting Fe particles having a diameter of 6 μm. The following findings were drawn from the present investigation: (i) the particle deposition on the vessel wall is greatly influenced by the intensity of the magnetic field, the magnet type, the magnet size, and the magnetic characteristics of the micro-sized magnetic particles (MSMPs); (ii) ferrite-type magnets might be employed to deliver magnetoresponsive particles to a target location, even if they are less powerful than neodymium magnets; and (iii) the results from the Computational Fluid Dynamics( CFD) models agree well with the measured magnetic field induction, magnetic field strength, and their fluctuation with the distance from the magnet surface.
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Garwood, Davis, Liyu Liu, Jirayu Mongkolkiattichai, Jin Yang, and Peter Schauss. "A hybrid Zeeman slower for lithium." Review of Scientific Instruments 93, no. 3 (March 1, 2022): 033202. http://dx.doi.org/10.1063/5.0081080.
Full textAbstract:
Zeeman slowers come in two commonly used types: electromagnet-based slowers and permanent-magnet slowers. Both have characteristic advantages and disadvantages. The electric currents required to create strong magnetic fields lead to heat dissipation that limits the achievable fields, while permanent-magnet slowers cause bias magnetic fields at the position of the magneto-optical trap. Here, we combine both approaches and their advantages at our lithium-6 triangular-lattice quantum gas microscope and extend the field of an electromagnet-based Zeeman slower using permanent magnets. We observe nearly doubled loading rates of the magneto-optical trap and no significant stray fields in the trapping region. Our approach allows for a stronger magnetic field in places where geometric constraints prevent the use of coils, and it provides a low-cost upgrade to the loading rate at established experiments.
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Phelan, Angie, Peter Petocz, William Walsh, and M. Ali Darendeliler. "The force-distance properties of attracting magnetic attachments for tooth movement in combination with clear sequential aligners." Australasian Orthodontic Journal 28, no. 2 (November 1, 2012): 159–69. http://dx.doi.org/10.2478/aoj-2012-0013.
Full textAbstract:
Abstract Background: The demand for clear sequential aligner therapy has increased dramatically in recent years. An improved system utilising small neodymium-iron-boron (NdFeB) magnetic attachments has been proposed to enhance appliance capabilities. Aim: The aim of the investigation was to analyse the force system diagrams produced by small attracting NdFeB magnets to determine, 1) whether the force levels were sufficient to induce tooth movement, 2) the effect of magnet morphology on force characteristics and, 3) the most appropriate magnet dimensions that could be utilised for this application. Methods: Twenty-nine NdFeB rectangular magnets of varying dimensions were tested. A Mach-1 universal testing machine (Biosyntech Inc, Quebec, Canada) was used to measure the attractive force of pairs of magnets. Measurements commenced with a magnetic pair in contact and subsequently vertically separated a distance of 10 mm at a speed of 12 mm/minute. For all magnetic configurations four repeat measurements were performed on five magnetic pairs of the same size. Results: The force-distance diagrams for all magnet configurations demonstrated a dramatic decrease in force with increasing magnet separation. Rather than a suggested inverse square law, the experimental data followed an inverse fourth law when an offset determined by a regression analysis was applied to the distance. For the majority of magnets, insignificant forces were attained beyond 2 mm of separation. Magnets with large pole face areas and longer magnetic axes provided the greatest force. Conclusions: A select range of magnet configurations exhibited suitable and reliable attractive forces and therefore could be advocated for prescribed clinical application.
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Saito, Tetsuji, Masahiro Tanaka, and Daisuke Nishio-Hamane. "Production of Mn-Ga Magnets." Materials 17, no. 4 (February 14, 2024): 882. http://dx.doi.org/10.3390/ma17040882.
Full textAbstract:
Mn-based magnets are known to be a candidate for use as rare-earth-free magnets. In this study, Mn-Ga bulk magnets were successfully produced by hot pressing using the spark plasma sintering method on Mn-Ga powder prepared from rapidly solidified Mn-Ga melt-spun ribbons. When consolidated at 773 K and 873 K, the Mn-Ga bulk magnets had fine grains and exhibited high coercivity values. The origin of the high coercivity of the Mn-Ga bulk magnets was the existence of the D022 phase. The Mn-Ga bulk magnet consolidated at 873 K exhibited the highest coercivity of 6.40 kOe.
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Li, Ziwei, Afef Kedous-Lebouc, Jean-Marc Dubus, Lauric Garbuio, and Sophie Personnaz. "Direct reuse strategies of rare earth permanent magnets for PM electrical machines – an overview study." European Physical Journal Applied Physics 86, no. 2 (May 2019): 20901. http://dx.doi.org/10.1051/epjap/2019180289.
Full textAbstract:
The global supply of heavy rare earth magnets can become risky with the soaring demand of rare earth permanent magnet (PM) machines. One of the promising solutions is to reuse or recycle permanent magnets from end-of-Life electrical machines. This paper is an overview study of the state-of-the-art permanent magnet reuse and recycling research for electrical machines. Some methodologies for quantifying the recyclability of permanent magnet of electrical machines are also introduced.