In this study, we investigated the characteristic changes in the restoring force characteristics with magnetic flux pinning phenomenon caused by changing the boundary conditions between multiple high-temperature superconductors. The magnetic flux pinning characteristics were investigated when a gap was provided between the superconductors and when a step was provided between the superconductors. At this time, a permanent magnet with a magnetic flux focusing arrangement was used as the floating body. As a result, it was confirmed that the restoring force characteristics due to magnetic flux pinning are improved under specific conditions. This revealed the usefulness of adjusting the boundaries between superconductors.

　The vibration mode called Intrinsic Localized Mode (ILM) is a phenomenon in which the vibration energy is concentrated at a localized point, which can be observed in a multi-massive dynamic vibration system connected by nonlinear springs. It is also possible to propagate the concentrated vibration energy to the adjacent masses under special conditions. Although ILM is a phenomenon with high engineering applicability from the viewpoint of vibration energy control, there are still few application research examples due to the low reproducibility of nonlinear springs. Therefore, we focused on the magnetic nonlinearity and proposed a nonlinear magnetic rotation spring for ILM excitation. In this paper, we present a prototype of the proposed magnetic spring and verify that the proposed model can excite the ILM.

　In recent years, a wide variety of motors have been used, but when manufacturing motors with different structures, it is necessary to make major changes to the winding manufacturing equipment, which causes an increase in cost. Therefore, the authors propose to manufacture the motor winding using a flexible PCB. In the proposed method, if there is no big difference in the structure and dimensions of the substrate, a winding with a high winding density can be easily manufactured at a relatively low cost. In this paper, we have manufactured a small magnetic levitation motor using windings manufactured using flexible PCB technology and investigated the effect of manufacturing error.

　This paper introduces a five-axis active-controlled axial-flux self-bearing motor that uses unipolar and four-pole magnetic fields to control radial force and tilt moment of the two-pole permanent magnet rotor. The proposed method controls the only one-axis radial force and tilt moment by a unit of the rotor and stator, therefore two units are necessary for radial motion control. The stators can be placed on the double-side and single-side of the rotor. In this paper, the principle of the proposed motor is introduced, and the radial force and tilt moment are analyzed theoretically. Then two experimental devices with double-side and single-side stators are made and levitation and rotation tests are carried out. The results confirm that the proposed motor achieved stable rotation up to 900 rpm in a double-side stator and 440 rpm in a single-side stator.

　The newly devised magnetic salient pole type thermomagnetic motor is analyzed using the finite element coupled analysis at the unsteady rotational operation. This thermomagnetic motor can generate torque by creating a temperature distribution with heating and cooling water in a rotor using a temperature-sensitive magnetic material and constructing a magnetic circuit in which permanent magnets are arranged to have magnetic salient poles. Multiple physical phenomena are coupled in driving a thermomagnetic motor, and the conditions for sustaining the operation are complicated. Therefore, sufficient knowledge is available about the rotational process of the rotor in the unsteady state from the stopped state to the steady rotation speed. This study analyzed unsteady rotational motion by the finite element method and examined whether stable driving is possible. It was confirmed that the rotor spontaneously rotates from the stopped state to the steady rotation speed under some heating and cooling temperatures and heat flux conditions. In addition, since it can rotate spontaneously, even if the flow rate of heating and cooling water changes during driving and the temperature distribution of the rotor changes, the temperature distribution of the rotor returns with time evolution due to the coupling of torque and rotation speed. Therefore, it was found that stable driving is possible.

　Currently, permanent magnet synchronous motors (PMSMs) are commonly used for EV traction motors. However, there are some problems in the cost of permanent magnets, high speed rotation, and the stable supply of rare earth resources. On the other hand, switched reluctance motors (SRMs) have simple, robust and inexpensive structure. However, SRMs have problems such as a large torque ripple, noise and vibration. In addition, SRMs are driven by a 3-phase asymmetric inverter, and the inverter cost is higher than a 3-phase inverter. Therefore, in order to solve these problems, we have proposed a 12/10 SRM that uses a hex connection and an improved 9-switch inverter. In this paper, a 12/10 SRM with hex connection for EV traction motors is designed and compared with induction machines (IMs). Finally, the difference between the SRM and IM is discussed.

　One of the technologies for detecting the position of railway vehicles is a sensor that obtains the position information by detecting a metallic marker laid on the track and an electromagnetic induction coil mounted on a railway vehicle. The maximum distance between the marker and the coil is 250 mm. One of the methods to improve the detection sensitivity is to increase the size of the excitation coil or to increase the excitation frequency. However, these methods have the problem of limiting the installation area and radiating electromagnetic waves to other equipment. Therefore, under the condition that the size and frequency of the excitation coil are constant, we evaluate the effect of the size of the coil and the metallic marker on the detection sensitivity and proposed a method to improve the detection sensitivity of the position detection sensor for railway vehicle.

　A bonded magnet is a permanent magnet molded by mixing magnetic powder and resin. Injection molding, one of the molding methods, has the advantage of greater freedom of shape than other molding methods, but it is difficult to understand the behavior of the resin during molding, resulting in variations in the density and magnetic properties of the molded product. Therefore, a coupled analysis method of the particle method and the magnetic moment method has been proposed to understand the resin behavior. In this study, we used this coupled analysis method to evaluate the behavior of resin during injection molding of bonded magnets in a cylindrical mold model with multiple injection ports placed at equal intervals.

　An ultra-compact ventricular assist device with an axial gap type self-bearing motor has been developed for use in pediatric circulatory support. The developed self-bearing motor has double stator structure to actively control five degrees of freedom (DOF) of levitated impeller postures and to enhance motor torque capacity with small device size which is 22 mm in outer diameter and 33.6 mm in total height, respectively. This study investigated magnetic suspension stability and energy consumption characteristics during pump operation with 3-DOF (z, θ_x, θ_y) control and 5-DOF (x, y, z, θ_x, θ_y) control. The axial position and inclination angles were sufficiently stabilized independently with the radial position control. The radial position control can be effective to suppress the radial whirling oscillation at resonance, however power consumption increased by up to 0.4-0.9 W compared to in the case of the motor utilizing 3-DOF control.

　This paper describes the application of a push-pull class-E amplifier to a transcutaneous energy transmission system for a totally implantable artificial heart using two-wire Archimedean spiral coil. To reduce the number of rectifier components in the power receiving circuit, the shape of the power receiving transformer was proposed. The calculations indicated that the power transmission efficiency including that of the power receiving circuit was increased, and the number of components in the power receiving circuit was reduced. In addition, the simulations indicated that the push-pull class-E amplifiers were able to obtain higher power than the general class-E amplifiers and supply sufficient power even when the input power supply voltage or load fluctuation occurs, by designing the amplifiers properly to fulfill the class-E operating conditions.

　Recently, the application of atmospheric pressure low temperature plasma to the medical field is expected, and the growth inhibitory action of cancer cells is indicated in the preceding research. In this study, colorectal cancer with many cases and deaths was noticed. The effect of plasma on colorectal cancer cells was evaluated by culturing colorectal cancer cells in a medium irradiated with atmospheric pressure low temperature plasma, expecting to induce proliferation inhibition or cell death. In addition, in this study, in order to examine the components affecting colorectal cancer cells, the concentration measurement of reactive oxygen species generated in the solution irradiated with plasma using the absorbance method was carried out. And, the mechanism of the cell reduction of the colorectal cancer cell induced by plasma was investigated.

　Transcutaneous energy transfer system (TETS) is one method of supplying electric power to a ventricular assist device. In this study, we analyzed the effects of internal electric fields on biological tissues around the TETS. The transmission frequency was fixed at 400 kHz, the transmission distance at 20 mm, the transmitting and receiving coils at 3 layers, and the output power at 15 W. The distance between the transmitting coil and the body surface was varied from 0.5 to 4.0 mm, and the output voltage was simulated at 24 V, which is the rated voltage of the VAD, and 14 V to suppress the internal electric field. The results showed that the internal electric field was the lowest when the distance was 4.0 mm and 14 V, and the maximum value was 18.68 V/m. This value was lower than the occupational exposure value of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines.

　This paper describes the development of a muscle-equivalent phantom for electrical impedance tomography (EIT). Conventional phantom adding titanium dioxide coated with antimony-doped tin oxide (ATO/TiO₂) cannot mimic the electrical properties of the human body over wide frequency band. The main material of the ATO/TiO₂-added phantom was changed from water to glycerol, and polyethylene powder (PEP) was added to decrease the relative permittivity of the medium, in order to expand the frequency band that can be mimicked. The electrical properties were measured for varying additions of glycerol, PEP and ATO/TiO₂, and the results agreed with the theoretical equations. Muscle-equivalent phantom for 10 kHz to 10 MHz were developed, and the errors in the electrical properties were 8.55% and −7.14% for relative permittivity and conductivity, respectively. The combination of a development phantom with a skin-equivalent phantom and a fat-equivalent phantom allows for more accurate evaluation of EIT devices.

　Electromagnetic waves are used in several applications; however many unanswered questions remain about the effects of electromagnetic waves on living organisms. One of the investigations of such biological effects is the evaluation of behavior when a living body is exposed to electromagnetic waves. A previous study shows that a magnetic field with a frequency of 400 kHz, field strength of 1 A/m, and an exposure time of 1 hour had no effect on the behavior of small laboratory animals (mice). In the present study, we investigated the effect of longer irradiation time than before. Mice with a locomotion meter implanted in their back were placed in a cage that generated magnetic field. Spontaneous locomotion and body temperature of mice were measured. Then we compared the results with spontaneous locomotion and body temperature in the absence of magnetic field exposure. As a result, the magnetic field reduced the spontaneous locomotion of mice and increased body temperature.

　Therapeutic endoscopy or surgical removal is possible up to stage T1, however, surgical treatment is no longer possible as cancer progresses, thus the prognosis is poor. There is an urgent need to develop new therapies to target advanced cancer or inhibit cancer progression. Several treatment methods for cancer currently exist, and in recent years, "plasma medicine" which uses plasma directly or indirectly, has been attracting attention. In this paper, we evaluate the use of Plasma Treated Saline (PTS) generation to study the therapeutic application of plasma to colorectal cancer.

　In order to construct a multiple-degrees-of-freedom system by using the motors with one degree of freedom, the same number of motors as the degree of freedom is required. On the other hand, a spherical motor has three degrees of freedom. It is possible to realize a system with three degrees of freedom by one spherical motor and, therefore, it can reduce the size of the system. A spherical speed reducer is necessary to change the output torque and motion speed of a multiple-degrees-of -freedom system. We have developed a spherical speed reducer capable of uniformly decelerating in all directions and demonstrated its applicability by speed reducing experiments using a prototype speed reducer. However, when the reduction ratio becomes large, the entire mechanism of the speed reducer will become large. Therefore, in this study, we investigated the optimization of the sphere arrangement so that the entire mechanism can be made as small as possible. This paper shows the objective function and constraint expression set from geometrical considerations. This paper also shows the analysis results of the change of the value of objective function by changing the arrangement of intermediate spheres placed between the rotor of a spherical motor and output sphere.

　Spherical actuators have many advantages such as high accuracy due to multiple-degree-of-freedom direct-drive and downsizing by reduction of the number of actuators. However, the conventional spherical actuators have complicated structures and control units. In order to solve these problems, we proposed a three-degree-of-freedom (3DOF) actuator driven by four-phase. The actuator can generate 3DOF motion by a four-phase inverter and four-coil. This paper describes a dynamic modeling and motion control method for the proposed 3DOF actuator. The simulation results showed that the actuator can be controlled in 3DOF by the proposed control method.

　Three-degree-of-freedom linear oscillatory actuator (3DOF-LOA) is expected to reduce the size and weight of haptic devices. However, it is necessary to generate a thrust spatially without force interferences from other axes, making it is difficult to reduce the number of parts and to simplify a supporting mechanism. To solve this problem, we propose a novel 3DOF-LOA consisting of two permanent magnets and three coils wound in layer. This paper describes the proposed magnetic structure and operating principle and clarifies the force and acceleration responses. As a result, it is confirmed that the proposed 3DOF-LOA can drive with asymmetric acceleration for the haptic presentation.

　In three-phase AC motors, three-phase AC voltage system is essential to generate a rotating magnetic field. Three-phase AC motors also require a three-phase inverter for variable speed and torque operation. In general, the number of switching devices used in three-phase inverter is not less than six and decreasing its number is difficult. This paper focuses on an LC ladder circuit consisting of linear inductors and capacitors. This paper presents a new operating method of the AC motor based on a propagating magnetic field. It is successfully excited by connecting one single-phase AC power supply to the end of the LC ladder circuit. The induction motor operated by the presented method produces torque as in general induction motors.

　The spherical synchronous actuator can be driven in multiple-degrees-of-freedom by a single unit. This simplifies the mechanism and is expected to be applied to industrial robots. The position of the actuator is controlled using a torque map which is a torque data at each posture. However, there is a problem that the positional accuracy is degraded by measurement errors in the torque map and friction. To solve this problem, we propose a novel attitude control system for the spherical actuator using a deep reinforcement learning algorithm. The simulation results showed that the control system was successfully implemented without a torque map. The system was able to follow the step response within 0.1 seconds, and the steady-state deviation was less than 0.1 degrees.

　Conventional manual transmissions suffer from deterioration due to wear and reduced responsiveness. Therefore, a linear electromagnetic actuator (LEA) for gear shifting has been developed. Since the LEA is a direct drive, it prevents deterioration due to wear and has high responsiveness. In addition, this LEA has a high holding force by detent force at three points. In this paper, sensorless position estimation is performed to simplify the system. Since one coil is not energized during driving in this LEA, so the back-EMF of the unenergized phase can be measured. We propose a sensorless position estimation method that focuses on the variation of the magnetic flux linkage characteristics in the position change. The simulation results show that the sensorless position control is possible.

　We developed a mechanism that convert rotation to linear motion by magnetic force of permanent magnet. The mechanism produces fluctuating torque to drive. We discovered driving two mechanisms that move onto opposite direction at the same time reduce the torque. We call that the way of driving with canceling the torque “Phase inversion drive method”. We investigated the effect of the method. To investigate that effect, we measured static force, static torque, dynamic torque, and power consumption of the mechanism. Compared with a way that drive single mechanism, amplitude of resistance torque is smaller when mechanisms are driven with the method. The effect that reduces resistance torque becomes stronger when linear motion is small. And that lead to reduce driving power consumption. It also reduces the amplitude of linear motion of mechanism that driving mechanisms fast. Therefore, torque reducing effect also become stronger when driving speed of mechanisms is fast.

　Multi-degree-of-freedom (multi-DOF) spherical actuators have been developed for the fields of robotics and industrial machines. We have proposed an outer rotor type three-DOF spherical actuator that can realize a high torque density. Each coil input current is calculated using a torque generating equation based on the torque constant matrix. The permanent magnet type actuators have a problem with generating unexpected cogging torque due to various manufacturing errors. Manufacturing errors mainly mean differences between the ideal dimensions at the motor design stage and the actual dimensions in mass production. In this case, the actuator would exceed the limitations of classical proportional-integral-differential (PID) controllers. Therefore, we propose a current compensator using reinforcement learning by introducing a deep neural network that is expected to improve the robustness of spherical actuators. This current compensator was applied to uncertainty problems such as manufacturing fluctuations of cogging torque.

　We are conducting research on the practical application of vibration power generation using magnetostrictive materials (Fe-Ga). The power generator, consisting of magnetostrictive material, U-shaped frame, coil and permanent magnet, has a simple structure and high output characteristics. However, vibration power generation is difficult to put to practical use because of the presence of environmental vibrations with multiple frequencies. The conventional generator is a single mass system, and when the frequency of the vibration source matches the resonant frequency of the generator, a large amount of power can be generated. For this reason, it is difficult to generate power efficiently when there are multiple vibration frequencies. Therefore, in this paper, we propose a generator for multi-mass point systems. The parameters are derived by optimization calculations to match the two natural frequencies of the generator to the target frequencies, and the evaluation of the power generation characteristics under real vibration is reported.

　Vibration power generation has been attracting attention as an environmental power generation method. On the other hand, there is a problem that stable power generation cannot be achieved due to changes in vibration frequency. In this study, we aimed to realize a wideband mechanism to cope with the frequency variation of magnetostrictive vibration power generation. For this purpose, we devised a stopper mechanism to contact the fixing bolts of the generator. We have demonstrated that this mechanism widens the bandwidth of power generation to the high frequency side. We have also demonstrated that the output power can be increased by adjusting the amplitude of the contact under vibrations with fluctuating frequency. This achievement means that magnetostrictive vibration power generation can be performed stably under actual vibration environments.

　Transcutaneous energy transfer system (TETS) is one of the methods to supply electric power to an assisted heart. In this study, we analyzed the effects of electric fields in the body on biological tissues around the TETS. Using an electromagnetic field simulator, biological tissue models consisting of Dry-Skin, Wet-Skin, Fat, and Muscle were fabricated. When the frequency was fixed at 400 kHz and the transmission distance at 20 mm, the analysis was conducted by changing the transmitting coils from 2 to 4 layers and the receiving coils from 1 to 4 layers in order to suppress the electric field strength inside the body. The results showed that the lowest internal electric field was observed at 2 layers of transmitting and 4 layers of receiving coils, and the maximum internal electric field was 77.07 V/m. This result was below the occupational of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guideline.

　It is necessary to take waterproof measures for the power supply coil and the power receiving coil used in undersea wireless power transfer. We have clarified the transmission characteristics of the coils in a waterproofed glass case. A spherical pressure-resistant glass is suitable for the high-water pressure of the deep sea. However, there are restrictions on the shape and size of the coil, as well as the installation location, in order to install a wireless power transfer system inside the sphere. Therefore, we could solve this problem by using a coil that is shaped along the exterior of the sphere. We call this coil the cone spiral coil. In this paper, the effect of the angular misalignment between coils on the transmission efficiency of underwater wireless power transfer using the cone spiral coil was analyzed by the finite element method and examined. The results show that the variation obtained by a conventional helical coil and the cone spiral coil was small.

　Wireless power transfer is applied to small mobile robots. Since the fluctuation of the received voltage is a problem in wireless power transfer to the small mobile robots, the suppression of the fluctuation is focused. In the magnetic resonant coupling method, it is necessary to match the resonant frequency of the primary side with that of the secondary side. The high Q value in the resonator causes voltage fluctuation due to the changes in load and/or distance. To solve this problem, the automatic tuning assist circuit (ATAC) is adopted to automatically adjust the resonance frequency, and the ATAC suppress the voltage fluctuation. In this paper, we focus on the inductance and capacitance of the ATAC system for wireless power transfer to small mobile robots and design the wireless power transfer system.

　When a momentary large current in opposite directions flows through the two opposing spiral coils, a momentary strong magnetic field in opposite directions is generated in the two coils. The strong magnetic field creates an impact force between the two coils. When a permanent magnet is placed under the spiral coils, the impact force of the actuator is enhanced because of the Lorentz force generated by the static magnetic field. In this paper, we introduce the principle of electromagnetic impact force generation and the calculation method of electromagnetic impact force. The magnetic fields generated by the spiral coil and the permanent magnet are analyzed by the finite element method. Then the electromagnetic impact force is derived from the current waveform and magnetic field. The shape of the spiral coil and permanent magnet is examined to maximize the electromagnet impact force.

　The purpose of this study is to improve the average torque and reduce the torque ripple by optimizing the design of the IPM motor to be compared using the Taguchi method, which is a quality engineering method. First, the parameters of the entire motor were optimized using the average torque as the evaluation value. Next, the details of the motor are optimized by considering the torque ripple. In the optimal design for improving the average torque, the average torque was improved by increasing the number of turns and increasing the slot area without reducing the magnetic flux. In the optimal design for reducing torque ripple, the stator teeth were made close to the closed slot and the gap length was increased by shortening the tooth edge.

　The superconducting magnetic levitation system is stable without control, but vibration suppression is required due to low damping caused by non-contact support. As a means of achieving this, electromagnetic shunt dampers composed of LCR electric circuits can be used to achieve effective vibration suppression without compromising the non-contact nature of the levitation system. However, since the velocity term is involved in the coupling between the kinetic and electrical systems, conventional vibration mode analysis cannot be used, and optimization of vibration control design becomes an issue. On the other hand, a method called non-classical mode analysis has been reported, which can be applied to systems that include coupled velocity terms. In this study, the behavior of a parallel shunt damper was investigated using this method, and it was found that dynamics of the system can be decomposed into two uncoupled modes of damped vibration.

　In general, shellfish contain a number of bacteria and viruses that can cause food poisoning. However, because raw food is so delicious, some people take the risk of eating it, and a certain number of cases occur every year. The bacteria that contaminates shellfish are known to concentrate in an organ called the digestive gland. If the organs can be sterilized with pinpoint heat, it will be possible to eat them safely while still enjoying the taste of eating raw food. Therefore, we investigated a method of heat sterilization of the digestive gland with pinpoint accuracy using a CO2 laser. As a result, 99.5% of the bacteria were sterilized.