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This paper describes comparison of thermal properties between Si power MOSFET and SiC power MOSFET. Conventionally, Si power MOSFET has been widely used in power electronics area. On the other hand, SiC power MOSFET has wide band gap, and is gaining attention as a new generation power device. However, thermal properties of SiC power MOSFET has not been clear. For appropriate thermal management of SiC power MOSFET, heat generation tendency and temperature rise of the device should be investigated. In this paper, we conducted numerical simulation to investigate thermal properties of SiC power MOSFET. Electro-Thermal Analysis was employed as simulation method. We compared temperature between Si power MOSFET and SiC power MOSFET, and discussed difference of heat generation and temperature between these two devices.

Molten-salt used as a coolant in fusion reactors plays a significant role in the design of advanced reactors. Investigation of thermal behavior is necessary in an actual environment of a facility where heat transfer enhancement takes place under a high Pr number fluid flow such as in case of FLiBe. For the development of a facility, it is necessary to be able to monitor fluid motion of a basic heat transfer promoter such as a sphere-packed pipe (SPP). In the present study, to discern the complex flow structures in SPP, digital holographic PTV visualization is carried out by a refractive index-matching method using a sodium iodide (NaI) solution employed as a working fluid. Hologram fringe images of particles behind the spheres can be observed, and the particles’ positions can be reconstructed by a digital hologram. Consequently, 3-D velocity-fields around the spheres are obtained by the reconstructed particles’ positions. The velocity between pebbles is found to be faster than that in other regions.

We review current accomplishments and ongoing work in Task 1–3 “Flow Control and Thermofluid Modeling” of the US-JAPAN “TITAN” Program. This encompasses construction of a new MHD lead–lithium loop at UCLA and planning, preparation and pre-experimental analysis for first experiments, including tests of high-temperature ultrasound Doppler velocimeter and studies of the behavior and electroinsulating properties of the foam-based silicon carbide flow channel insert in the flowing liquid metal in a magnetic field. First results of magnetohydrodynamic experiments on flow transitions from 3D to 2D are also presented and discussed.

The NDT method using electromagnetic waves has availability for crack detection in large pipes or structures in nuclear power plants. The purpose of this study is then, to develop a new method to determine the crack size and location with high speed and accuracy. Through this study, it has been shown that the transmitted wave carries a lot of information on crack depth and the obtained signals of reflected wave below the cut-off frequency depend on the crack position. Experimental results indicate that there exists attractive possibility in the new NDT method.

A significant increase of mRNA expression of thymic stromal lymphopoietin (TSLP) has been reported in the bronchial mast cells (MCs) of asthmatic subjects; however, the mechanism underlying the upregulation of TSLP mRNA and protein remains unknown. FcepsilonRI-mediated activation of human MCs upregulated TSLP mRNA expression by 5.2+/-2.9-fold, while activation of the MCs using lipopolysaccharide and polyriboinosinic:polyribocytidylic acid failed to upregulate TSLP. Stimulation of MCs with interleukin (IL)-4 alone did not affect the TSLP mRNA expression, while pre-incubation of MCs with IL-4 for 48 h significantly enhanced the FcepsilonRI-mediated TSLP mRNA expression (by 53.7+/-15.9-fold; p0.05) and the amount of TSLP in the cell pellets increased significantly from 23.4+/-4.3 pg mL(-1) to 121.5+/-3.7 pg mL(-1) (p0.0001). However, the released TSLP was rapidly degraded by proteases that were released by MCs. We identified the population of cells expressing TSLP in the lungs of 16 asthmatic and 11 control subjects by immunohistochemistry. The percentage of TSLP-positive MCs in the total population of MCs was significantly increased in asthmatic airways (p0.0001). Thus, MCs are able to store TSLP intracellularly and to produce TSLP following aggregation of FcepsilonRI in the presence of IL-4.

This paper evaluates the control performance of a speed sensorless induction motor control method for railway vehicles traction, compared to vector control system with pulse generators as speed sensors, from the view points of flux behavior. The speed sensorless strategy is based on the rotor flux induced voltage and is expected its high performance as well vector control system with pulse generators. The control performance is verified from the viewpoint of the rotor flux, because the speed sensor is used for controlling the rotor flux with the indirect vector control strategy. This paper provides the way how to evaluate the speed sensorless control on the railway vehicle traction system. First, the proposed speed sensorless control strategy for railway vehicles is presented. Then, its basic control characteristic is evaluated by numerical simulation and further control functions that are peculiar to the railway traction application are rated by the experiments

For railway vehicle traction purpose, slip frequency of induction traction motors are controlled with detecting rotor frequency by pulse generators or PGs as the speed sensors. Applying the speed sensor less control method to the railway vehicle traction to eliminate the PGs, we expect to improve cost efficiency and reliability of the traction control system. Though speed sensor-less control methods are popular in general industrial application purpose, some novel control functions may be added and its compatibility is verified to cope with the problem particular in railway vehicle traction application. In this paper, we present the result of the application to railway vehicle traction control with theoretical study and tests.

No case of histopathologically confirmed delayed cerebral radiation necrosis (DCRN) that occurred twice at different regions and times in the same patient has been previously reported. We present a patient with such a rare clinical course and who is surviving long-term (over 13 years) with a history of a distant metastasis of a malignant tumour. To diagnose DCRN preoperatively was very difficult. However, surgical extirpation seemed to be effective for DCRN. The patient is still in a good performance status after surgery.

We have observed an oscillation in the current density–voltage (J–V) characteristics caused by resonant tunneling phenomena by means of a newly developed Si‐based double barrier structure (DBS). In the DBS fabrication, a thin single‐crystal Si plate is used as a quantum well on SIMOX (separation by implanted oxygen) substrate. In order to obtain the Si quantum well, an anisotropic wet chemical etching followed by thermal oxidation is performed. Particularly, a novel advanced shaped etching mask is used to form an extremely thin Si plate. The width of the plate exceeds the resolution limitation of lithography. Accordingly, a quantum well with a width of 9 nm has been successfully obtained. The electrical characteristics of the sample that has around 40 nm wide quantum well and 1.6 nm thick SiO2 barriers are investigated. Oscillation peaks are observed in the J–V characteristics at 4.0 K. The observed peaks are in good agreement with the calculated resonant tunneling diode model.

Construction of a highly accurate segment companding voice codec is described in this paper. It is shown that an ideal precompressor placed in front of the segment coder enables moderating the accuracy required by 4 times in the 13-segment coder and by 8 times in the 15-segment coder. Two precompressor circuits with a negligible accuracy degradation are proposed and their performances are thoroughly discussed. It is shown that highly accurate sequential feedback segment companding coders, such as the 8-bit 13- or 15-segment coder, can be realized easily with these precompressors.