In order to achieve high rate deposition of Ni-Zn ferrite thin-films in reactive sputtering, a conic target with a sputtering area of 750 cm² was equipped in an ECR (electron-cyclotron-resonance) sputtering apparatus. Highly oriented Ni-Zn ferrite thin-films with a saturation magnetization of 290 emu/cc, a low coercivity of 11 Oe, and a relatively small stress of 4 × 10⁹ dynes/cm² could be prepared at a substrate temperature of 250 °C and a high deposition rate of 44 nm/min. It was found that saturation magnetization and coercivity of the Ni-Zn ferrite thin-films strongly depend on the reduced process parameter: oxygen partial pressure divided by deposition rate.

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We studied MnZn ferrites for high-performance deflection yokes, using recycled disposable dry-cell batteries as raw materials. Many dusters existed after milling of the batteries caused deterioration of the magnetic properties. However, after further milling, clusters were broken into minute particles, a fine powder was obtained, green density, sintered density and saturated magnetic flux density increased and core loss decreased. Furthermore, by optimization of each manufacturing process, higher quality was realized than conventional materials were used.
Since, environmental destruction is a major contemporary social problem, it can be said that this technology promoting the recycling of dry-cell batteries is a useful advance in that it can contribute to the protection of the earth.

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We developed a jaw-tracking system consisting of two magnets and biaxial fluxgate sensors. One magnet is fastened to a tooth in the bottom jaw of the subject and another is fastened to the subject’s forehead. The system can naturally detect movement of the jaw as a rigid body. We fabricated sensor arrays with separate upper and lower parts in order to obtain good position accuracy. Positional accuracy to within 0.1 mm was achieved as a rigid body using a jaw model. Six degrees of freedom and 100 Hz sensing cycles were achieved using one rigid marker (composed of two magnets), and achieved position accuracy to within 0.3 mm.

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The impedance of a magnetic thin film changes when a magnetic field is applied. The high-frequency carrier magnetic field sensor, also called a GMI sensor, employs this phenomenon as its principle; it acts as previously a high-sensitivity magnetic field sensor. We detected the impedance by an amplitude-modulation method. As changing the impedance also changes a phase difference, we directed our attention to this phenomenon and measured the magnetic field by measuring the phase difference. The sensor element used was a meander pattern (thickness: 4.1 μm, length: 1mm, width: 20 μm, unit distance: 50 μm, number of turns: 3), which was fabricated on a CoNbZr thin film by a lift-off process. The high frequency of the carrier signal made it difficult to measure the phase difference correctly. We coverted the carrier frequency to a low frequency by the dual-mixer time-difference method and calculated the phase difference by measuring interval time. The best rate of change is 5.24 degrees/Oe at 7.8 Oe when the carrier frequency is 158 MHz. As the jitter error of this system is 5.51×10^-4 degree and the sampling rate is 1 ksample/sec, the resolution of this system is 3.32 × 10^-6 Oe/√Hz.

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This paper introduces a method for measurement of flow velocity using nuclear magnetic resonance (NMR) imaging. In a zinc electrodeposition bath, a convection of ZnSO₄ solution was generated at a Rayleigh number of 2.7 × 10¹¹. The electrolytic bath had a pair of horizontal zinc electrodes with a radius of 13 mm. Stejskal-Tanner plots of the fluid were measured with q gradients up to 41.5 mm^-1. Probability density functions (average propagators) of the displacement of fluid in the q gradient interval Δ = 20 ms were obtained by Fourier transform of the Stejskal-Tanner plots. The half bandwidths of the average propagators with and without convection were 4.6 × 10^-2 mm and 3.6 × 10^-2 mm, respectively. Maps of the x, y, and z components of the flow velocity were calculated from phase maps. The half bandwidth of the average propagator obtained from the flow velocity map was 5.1 × 10^-2 mm. These methods enable non-invasive and quantitative evaluation of transport phenomena by convection in electrodeposition processes.

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The magnetic properties of a motor core are affected by the distortion due to the compression caused by bolt bundles. There have been few reports of such behavior being investigated systematically, although detailed examination of the behavior of magnetic properties is important. In this paper, the correlation between the compressive force of a silicon steel sheet and its magnetic properties is measured, using some single sheets compressed in the thickness direction. A special jig was prepared, and the magnetic field strength in the compressed region was measured using a Rogowski coil. The detailed behavior of the deterioration of the BH curve the iron loss due to cutting, and the compression caused by bolt bundles are illustrated.

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We developed spiral-type transmission line device consisting of a spiral winding with a polyimide dielectric film, a ground plane, and a Mn-Zn ferrite pot core. To analyze the transmission characteristics of the devices, we introduced a coupled distributed constant circuit model. Differential equations for voltage and current obtained from the analysis model include impedance and admittance matrixes representing electromagnetic coupling between different turns. As a result, the calculated transmission characteristics agreed well with the measured ones.

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The implant medical device discussed here is an artificial sphincter that utilizes shape memory alloy (SMA). This device is implanted into the body of a patient to provide independent evacuation for a patient using an artificial anus. The artificial sphincter operates based on the phase transformation of the SMA that occurs when it is heated. The phase transformation completion temperature of the SMA that we used is 55°C. To prevent the SMA from being overheated in a living body, a transformer utilizing thermosensitive ferrite is used as a temperature control device. In an earlier prototype, we confirmed that temperature control of the SMA was possible. We examined suitable core design and composition. The transformer core type is composed of a hybrid core that uses thermosensitive Ni-Cu-Zn ferrite (Curie-point T_c = 60°C) and non-thermosensitive Mn-Zn ferrite. Effective saturation magnetic flux density of the thermosensitive ferrite and the Mn-Zn ferrite are 250 mT and 520 mT respectively at room temperature. Class 10 W power transmission is possible through this small transformer. When the temperature of the SMA is higher than T_c, magnetization of the thermosensitive ferrite disappears and power transmission to the heater weakens.

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This paper describes a new method for discriminating among multiple sources in the brain overlapping in time. We carried out a three-dimensional vector measurement of bilateral somatosensory evoked field (SEF) with an electric stimulus to the right thumb, using three-dimensional second-order gradiometers connected to 39-channel SQUIDs, which can detect magnetic components perpendicular to the scalp (Br) and tangential to the scalp (Bθ, Bφ) simultaneously. The SVD method was applied to each spatiotemporal datum, having two frequencies ranges (1-40Hz, 15-40Hz), with a time window (50 ms) and was shifted every 5 ms in analysis. Two dominant singular values were obtained for the contralateral magnetic component. We applied a time-frequency analysis to bilateral magnetic data and analyzed the time course of the power spectrum. We concluded that this proposed method, using a dynamic SVD method and time-frequency analysis with different frequency ranges, is useful for discriminating among multiple sources overlapping in time.

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Three-dimensional vector measurement of exercise-induced magnetocardiograms (MCGs) of normal subjects were performed by using a bicycle ergometer made of wood and brass.
MCGs were measured by a three-dimensional second-order gradiometer connected to 39-channel SQUIDs, which can detect magnetic components perpendicular to the chest wall (Bz) and tangential to the chest wall (Bx, By) simultaneously. MCG data of normal subjects were analyzed by using time-frequency analysis and found that the power spectrum of the ST segment was different between rest times and exercise-induced stress for the heart. PCA was also applied to the result of time-frequency analysis and the time course of frequency for the QRS and ST segments were evaluated quantitatively.

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