We investigate spin transfer torque (STT) in magnetic multilayer structures using micromagnetic simulations. We implement the STT contribution for magnetic multilayer structures in addition to the Landau-Lifshitz-Gil-bert (LLG) micromagnetic simulators. In addition to the Sloncewski STT term, the zero, first, and second order field-like terms are also considered as well as the effects of the Oersted field due to the running current are addressed. We determine the switching current densities of the free layer with the exchange biased syn-thetic ferrimagnetic reference layers for various cases.

CoNiFe(CNF)/BaTiO₃(BTO)/CoNiFe(CNF) multilayered thin films were deposited on Pt/Ti/SiO₂/Si substrates by using pulsed laser deposition (PLD) system. We fabricated three different thin films of BTO, BTO/CNF and CNF/BTO/CNF for magneto-capacitor and studied their crystalline structure, surface and interface morphol-ogy, and magnetic and electrical properties. When three different structures of multilayered thin film were compared, magnetization of CNF/BTO/CNF thin films was decreased by magnetic and dielectric interaction. Also we confirmed that capacitance of CNF/BTO/CNF multilayered thin film was enhanced as being near tet-ragonal structure with increasing of c/a ratio because of atomic bonding at interface between BTO dielectric and CNF magnetic materials. Finally, we studied the change of the capacitance of CNF/BTO/CNF multilay-ered thin film with magnetic field for emergence of magnetocapacitance and suggested a possibility of enhanced capacitance.

Magnetic particles in a novel, wound–healing ointment were studied using Mössbauer spectroscopy and VSM to estimate the stability of the properties of the magnetic particles. The isomer shifts of Fe₃O₄(A) were found to be 0.49-0.56 mm/s relative to iron metal, this indicates that the iron ions in Fe₃O₄(A) are Fe³⁺. On the other hand, the isomer shifts of Fe₃O₄(B) were found to be 0.91-1.13 mm/s relative to iron metal, this shows that the ion state of Fe₃O₄(B) is a mixed state of Fe²⁺ and Fe³⁺. It is noted that this composition, as well as that of the ini-tial pure component in the form of a highly dispersed fraction (~10 Å), differs from the stoichiometric one. It was found that the area ratio of the Mössbauer subspectra of Fe₃O₄(A) / Fe₃O₄(B) taken at 87 and 181 K lin-early increased in comparison to the initial pure magnetic particles, but the rate of increase of the area ratio at 181 K was about two times that at 87 K. From the magnetic hyperfine field, despite their small size, the parti-cles exhibit no superparamagnetism.

This study investigated the effects of adding a third alloying element, Ni, to create Fe_70-xPd₃₀Ni_x (x = 2, 4, 6, 8 at.% Ni) ferromagnetic shape memory alloys (FSMAs). The Ni replaced a portion of the Fe. The Fe_70-xPd₃₀Ni_x alloys were homogenized through hot and cold forging to gain a ~38% reduction in thickness, next they were solution-treated (ST) with annealing recrystallization at 1100 ℃ for 8 h and quenched in ice brine, and then aged at 500 ℃ for 100 h. Investigation of the microstructures and magnetostriction indicated that the greater Ni amount in the Fe_70-xPd₃₀Ni_x alloys reduced saturation magnetostriction at room temperature (RT). It was also observed that it was more difficult to generate annealed recrystallization. However, with greater Ni addition into the Fe_70-xPd₃₀Ni_x (x = 6, 8 at.% Ni) alloys, the L1₀+L1_m twin phase decomposition into stoichiometric L1₀+L1_m+α_bct structures was suppressed after the 500 ℃/100 h aging treatment. The result was that the Fe_70-xPd₃₀Ni_x (x = 6, 8 at.% Ni) alloys maintained a high magnetostriction and magnetostrictive susceptibility (Δλ_||^s/ΔH) after the alloys were aged at 500 ℃ for 100 h. This magnetic property of the Fe_70-xPd₃₀Ni_x (x = 6, 8 at.% Ni) alloys make it suitable for application in a high temperature (T > 500 ℃) and high frequency environ-ments.

The change of saturation magnetization in boronized low carbon microalloyed steels was investigated as a func-tion of boronizing time. Specimens were boronized in an electrical resistance furnace for times ranging from 3 to 9 h at 1123 K. The metallurgical and magnetic properties of the specimens were investigated using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and vibrating sample magne-tometry (VSM). A boride layer with saw-tooth morphology consisting of FeB and Fe₂B was observed on the surface, its thickness ranged from 63 ㎛ to 140 ㎛ depending on the boronizing time. XRD confirmed the presence of Fe₂B and FeB on the surface. The saturation magnetization decreased with increasing boronizing time. This decrease was attributed to the increased thickness of the FeB and Fe₂B phases. Cracks were observed at the FeB/Fe₂B interfaces of the samples. The number of interfacial cracks increased with increasing boronizing time.

Flux concentrated permanent magnet transverse flux machines, FCPM-TFMs, with segmented stators require multi-turn concentric saddle coils to replace the ring coils, which are normally utilized in conventional layered-phase TFM constructions. In this paper, we investigate the influence of the shape of saddle phase windings and their parameter variations on the output torque productivity. Non-meshed coils evaluated via a finite element method (FEM) to examine the effect of the coil’s location within one phase on machine performance. By using meshed coils, the analysis can be extended to inspect the distributions of magnetic field strength as well as cur-rent density in the coils. Throughout the study, the influence of design parameters on the output torque for two stator structures, i.e., a laminated and soft magnetic composite (SMC), are evaluated.

The torque characteristics of a surface-mounted permanent magnet synchronous motor (SPMSM) are ana-lyzed in this study. The harmonics of the back electromotive force (EMF) and cogging torque are analyzed by the finite element method to study their effects on the torque ripple. Although low cogging torque can be achieved by varying geometric parameters such as the permanent magnet (PM) offset and notch depth on the stator teeth, the torque ripple is increased in some cases. The analysis results show that the ripple of the gener-ated torque is determined by not only the amplitudes but also the phases of harmonics for the back EMF and cogging torque.

Contactless electrical power transfer through an air gap is a revived technology for supplying energy to many movable applications including Maglev. In this paper, magnetic equivalent circuits and analytical models of contactless electrical power transfer systems are developed and evaluated through experiment. Overall cou-pling coefficient and overall efficiency are introduced as means for evaluating the systems’ performance. Com-pensating capacitors in primary and secondary sides of the systems improve the overall coupling coefficient and overall efficiency. Using the analytical models, the effects of different parameters and variables such as air gap and load current are analyzed to give a high coupling coefficient and an improved efficiency of power transfer for different compensation structures.

Many different converter topologies have been developed with a view to use the minimum number of switches in order to reduce construction costs. Among this research, the four-switch converter topology with a novel PWM control technique based on the current controlled PWM method is thought to be a good solution. In this paper, a two dimensional time-stepped voltage source finite-element method (FEM) is used to analyze the characteristics of a Flux-Reversal Machine (FRM) with a 4-switch converter. To validate the proposed computational method, a digital signal processor (DSP) installed controller and prototype FRM are built and experiments performed.

To evaluate the electromagnetic power absorption in near field, the magnetic composites with the conductive grids were simulated using the typical permeability frequency profiles. The transmission power absorptions of the magnetic composites on microstrip line were extracted by the 3D FEM simulation program of HFSS. The magnitudes of power absorptions were greatly enhanced up to 98% and broadened the absorbing frequency band over 5 GHz by the insertion of a conductive grid in magnetic composite. The initial frequency of the power absorption can controlled by the change of the ferromagnetic resonance frequencies of the magnetic composite.

We investigated the effects of pulsed magnetic fields (PMF) stimulus on electroencephalogram (EEG) alpha activity and heart rate variability (HRV) from electrocardiogram (ECG) measurements with various stimulus durations at acupoint PC9. The alpha activity in the EEG and the ratio of low frequency power and high frequency power (LHR) in the HRV, a reflection of sympathovagal activity, were increased and decreased,respectively, after PMF stimulus of 3 min. Our spectral analysis quantitatively proved that the changes in the EEG alpha activity were consistent with an autonomic function in the ECG. These findings suggest that appropriate PMF stimulus results in the same effect as that of acupuncture applied to the acupoint PC9, which is closely related to the parasympathetic activity of the autonomic nervous system.

3-dimensional magnetic resonance cholangiopancreatography (MRCP) images reconstructed using the maximum intensity projection technique were analyzed qualitatively in patients diagnosed with pancreatobiliary diseases to determine their diagnostic utility. Single shot fast spin echo (SSFSE), fast spin echo (FSE) and 3-dimensional reconstructive images were acquired from 20 patients diagnosed histologically with pancreatobiliary diseases using a 3.0T MR scanner. According to qualitative analysis, the fast spin echo images and 3-dimensional reconstructed images of the hepatic duct, gall bladder and common bile duct had a higher signal to noise ratio (SNR) than the single shot fast spin echo images. Fast spin echo images and 3-dimensional reconstructed images did not show any differences. The contrast to noise ratio of the hepatic duct, gallbladder and common bile duct on the fast spin echo images and 3-dimensional reconstructed images was higher than that of the single shot fast spin echo images. The fast spin echo images and 3-dimensional reconstructed images showed similar quality.

Patients who underwent hip arthroplasty using the conventional fat suppression technique (CHESS) and a new technique (IDEAL) were compared quantitatively to assess the effectiveness and usefulness of the IDEAL tech-nique. In 20 patients who underwent hip arthroplasty from March 2009 to December 2010, fat suppression T2 and T1 weighted images were obtained on a 3.0T MR scanner using the CHESS and IDEAL techniques. The level of distortion in the area of interest, the level of the development of susceptibility artifacts, and homoge-neous fat suppression were analyzed from the acquired images. Quantitative analysis revealed the IDEAL tech-nique to produce a lower level of image distortion caused by the development of susceptibility artifacts due to metal on the acquired images compared to the CHESS technique. Qualitative analysis of the anterior area revealed the IDEAL technique to generate fewer susceptibility arti-facts than the CHESS technique but with homogeneous fat suppression. In the middle area, the IDEAL tech-nique generated fewer susceptibility artifacts than the CHESS technique but with homogeneous fat suppression. In the posterior area, the IDEAL technique generated fewer susceptibility artifacts than the CHESS technique. Fat suppression was not statistically different, and the two techniques achieved homogeneous fat suppression. In conclusion, the IDEAL technique generated fewer susceptibility artifacts caused by metals and less image distortion than the CHESS technique. In addition, homogeneous fat suppression was feasible. In conclusion, the IDEAL technique generates high quality images, and can provide good information for diagnosis.

This study evaluated the ability of Diffusion-Weight Image (DWI), which is one of pulse sequences used in MRI based on the T2 weighted images, to detect samples placed within phantoms according to their size. Two iden-tically sized phantoms, which could be inserted into the breast coil bilaterally, were prepared. Five samples with different sizes were placed in the phantoms, and the T2 weighted images and DWI were obtained. The Breast 2 channel coil of SIEMENS MAGNETOM Avanto 1.5 Tesla equipment was used for the experiments. 2D T2 weighted images were obtained using the following parameters: TR/TE = 6700/74 msec, Thickness/gap = 5/1 mm, Inversion Time (TI) = 130 ms, and matrix = 224 × 448. The parameters of DWI were that TR/TE = 8100/90 msec, Thickness/gap = 5/1 mm, matrix = 128 × 128, Inversion Time = 185 ms, and b-value = 0, 100, 300, 600,1000 s/mm. The ratio of the sample volume on DWI compared to the T2 weighted images, which show excellent ability to detect lesions on MR images, was presented as the mean b-value. The measured b-value of the samples was obtained: 0.5 × 0.5 cm = 0.33/0.34 square × cm (103%), 1 × 1 cm = 1.28/1.25 square × cm (102.4%),1.5 × 1.5 cm = 2.28/2.67 square x cm (85.39%), 2 × 2 cm = 3.56/4.08 square x cm (87.25%), and 2.5 × 2.5 cm =7.53/8.77 square × cm (85.86%). In conclusion, the detection ability by the size of a sample was measured to be over 85% compared to T2 weighted image, but the detection ability of DWI was relatively lower than that of T2 weighted image.

Although 3.0T magnetic resonance imaging (MRI) has the advantages of a higher signal to noise ratio (SNR) and contrast than 1.5T MRI, there are limitations on the contrast between white and grey matter because of the long T1 recovery time when T1 images are obtained using the Spin Echo Technique. To overcome this, T1 weighted images are obtained occasionally using the inversion recovery (IR) technique, which employs a rela-tively long TR. The aim of this study was to determine the optimal TI in a brain examination when a T1 weighted image is obtained using the IR technique. Eight participants (male: 7, female: 1, average age: 34 ± 14.11) with a normal diagnosis were targeted from February 18, 2012 to February 27, 2012, and the con-trast between white and grey matter as well as the contrast to noise ratio (CNRs) in each participant were mea-sured. The CNRs of white matter and grey matter were highest at TI = 600, 650, 750, 900, 1050 and 1100 ms when the TR was 1100, 1400, 1700, 2000, 2300 and 2600 ms, respectively. Therefore, as the TIs were 44.425 ± 0.877% of the TRs in the TR range of 1400-2300 ms, the optimal T1 weighted images that describe the contrast between white and grey matter can be obtained if the TIs are compensated for with 44.425 ± 0.877% of the TRs in the time of setting TIs.