Permanent magnets are used for generating magnetic flux without consumption of energy in electrical machines. The flux from a magnet decreases by exposure(s) to elevated temperatures and/or magnetic fields. It also decreases over time. This phenomenon is called “flux loss”. In this contribution, the mechanism of flux loss is explained, and the relationship between flux loss and basic magnetic properties of a magnet is clarified. Subsequently, the prediction method of flux loss is discussed from the viewpoint of basic magnetic properties. Finally, examples of prediction of flux loss using the finite element method are shown for multi-pole ring magnets placed in free space and in a motor.

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　High-performance rare earth bonded magnets, along with sintered counterpart, have been playing an important role in the technological innovations for ICT (Information and Communication Technologies), FA (Factory Automation), automotive, and green technology areas. Three types of bonded magnet materials; Sm-Co, Nd-Fe-B, and Sm-Fe-N, were commercialized, and their worldwide production has now reached about 10,000 ton/year. In this paper, features and application examples of the rare earth bonded magnets are described.

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　Meta-stable iron nitride, α”-Fe₁₆N₂, which has high saturation magnetization and moderate magnetic anisotropy, is one of the possible candidates for alternative material with rare metal/rare earth element less/free. In this paper, intrinsic magnetic properties such as saturation magnetization and magnetic anisotropy field are briefly presented based on our work in powder form, in addition to extrinsic magnetic properties such as residual magnetization and coercivity in bulk magnet form.

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　We will explain the magnetization of permanent magnets, from the basics of magnetism to the method of magnetization. We will also explain the principles of the effects of eddy currents and Lorentz forces as points to note during magnetization. Finally, we will also explain typical magnetic measurements after magnetization.

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　Magnetic fluids have their many industrial applications in field of thermo-fluid engineering. Particularly there is one that has the strong temperature dependence on the magnetization at room temperature range, so called temperature sensitive magnetic fluid, TSMF. TSMF whose magnetic constituent that contains high pyromagnetic coefficient can also be extended to various applications in thermo-fluid engineering, by controlling both magnetic and temperature filed simultaneously. Present report describes some representative systems those produce power or refrigeration by cycling a ferromagnetic material or TSMF itself, thermally through a range of temperatures such that its magnetization changes appreciably. The present report also introduces and discuss some representative devices in such magnetic heat transport and refrigeration device in conjunction with development of permanent magnet. Hybrid combination with the magnetic material itself and magnetic field distribution in the devices are discussed for further development of engineering utilization.

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　In recent years, studies on magnetic levitation have attracted much attention. One of them is a study on magnetic levitation systems for thin steel plates. The background of the research is that conveyance using rollers is mainly used in the manufacturing process. In this process, contact between the rollers and the thin steel plate may cause scratches on the steel plates surface. Non-contact gripping and conveyance using magnetic levitation technology has been proposed to prevent surface quality deterioration of thin steel plates. The magnetic levitation system for thin steel plates proposed by the authors was able to suppress deflection of thin steel plates compared to conventional systems. However, the number of electromagnets used is reduced. This may affect the levitation stability. In this report, changes in the levitation characteristics of the proposed magnetic levitation system for thin steel plates are considered.

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　Hyperthermia is used in combination with medication in the treatment of cancer. Hyperthermia has less effect on the human body than other therapies, and further improvement is required. When developing hyperthermia, it is necessary to demonstrate the effects of hyperthermia on the human body. However, since experiments using the human body or animals are often avoided due to ethical issues, the use of a phantom that simulates the electrical properties (relative permittivity and conductivity) of the human body is useful as a solution. Therefore, the purpose of this study was to develop a phantom equivalent to a heated liver at 8 MHz, which is currently widely used in hyperthermia. The electrical properties were simulated within 10% error at each temperature.

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