Haruhiko Okumura

• PhD
• Professor (Full) at Mie University

According to the national syllabus set forth by the Ministry of Education, Culture, Sports, Science and Technology, or hence force MEXT for short, and implemented in senior high schools since the school year of 2003--2004 in Japan, every student is expected to study and acquire necessary credits for the newly established subject Information Study....

Plasma diagnostic data analysis often requires the original raw data as they are, in other words, at the same frame rate and resolution of the CCD camera sensor. As a non-interlace VGA camera typically generates over 70 MB/s video stream, usual frame grabber cards apply the lossy compression encoder, such as mpeg-1/-2 or mpeg-4, to drastically less...

Measurements of the magneto-Seebeck coefficient and magnetoresistivity of two bismuth microwire arrays having different diameters and a bulk sample were performed for applied magnetic fields between 0 and 2 T and temperatures between 50 and 300 K. The magneto-Seebeck coefficients were always enhanced as a result of controlling the phonon scattering...

Distributions of the velocity, the temperature and the pressure of a liquid nitrogen (LN2) flow are analyzed at hydraulic cross-sections on two types of superconducting power transmission lines (SC PT). One is on a DC-SC PT, the other is on a three phase AC-SC PT. Inflow heat from the pipe wall and the cables to LN2 are evaluated, however the heat...

We are promoting projects in combination with Squeak eToys, visual programming software for children and Field Server, remote monitoring system for edible vegetation. We developed a Squeak interface with Field Servers, the remote environment monitoring equipments developed by the National Agricultural Research Center of Japan and installed througho...

To support the steady-state plasma experiments in LHD, new functions have been developed for the LABCOM data acquisition system. Using new WE7000 and PXI digitizers for continuous ultra-wideband data acquisition at 80 MB/s, the system is now able to perform data acquisition, storage, and server-to-client transfer fully in real-time. To manage the h...

Peltier current leads (PCL) were applied to a cryogen-free superconducting magnet (CFM) of 5 T/90 A. We measured the temperature profiles on the current lead of the CFM. Compared with the conventional copper current lead, the PCL reduced the temperature and the temperature gradient on the first stage of the cryocooler of the CFM at zero current. Th...

We have installed Peltier current leads (PCLs) in a commercial, cryogen free magnet to reduce heat flow to the GM cooler. Experimental results show that the first stage temperatures of the GM cooler are lower with the application of the PCLs than with conventional current leads (CCLs). At each operating current, from 0 to 75 A, the temperature grad...

We investigate data compression algorithm for astronomical satellite mission JASMINE. We are required to use lossless compression algorithms for scientific data. We cannot use lossy compression schemes which recently develop with the advance of internet technologies. Astronomical data is mainly image data, and it is binary data. Consequently, we mu...

In fusion experiments, diagnostic control and logging devices are usually connected through the field bus, e.g. GP-IB. Internet technologies are often applied for their remote operation. All equipment and digitizers are driven by pre-programmed sequences, in which clocks and triggers give the essential timing for data acquisition. Data production r...

For the reduction of heat leakage via the current leads to superconducting magnets, several researches of the Peltier Current Lead (PCL) were performed, and demonstrate the principle of the PCL to reduce the heat leakage experimentally and numerically. The shape dependences were evaluated by using the ratios of the length and the cross section (L/A...

Peltier current lead is a promising method to reduce heat leakage from current lead. This paper reports development of Peltier current lead (PCL) with switching facilities to adopt the PCL to polarity-reversible superconducting magnet. In the present work, two types of the PCL were discussed. We mainly investigated the PCL with switching element in...

This paper describes how to typeset Chinese, Japanese, and Korean (CJK) languages with Omega, a 16-bit extension of Donald Knuth's TEX. In principle, Omega has no difficulty in typesetting those East Asian languages because of its internal representation using 16-bit Unicode. However, it has not been widely used in practice because of the difficult...

Many applications of superconductivity are studied because they are basically nondissipative systems; however, electric power is spent to keep them at low temperature. If heat leakage is high, the advantage of the superconductivity will be reduced or disappear, and therefore we must reduce the heat leakage as much as we can in the actual system. Th...

This paper describes how to typeset Chinese, Japanese, and Korean (CJK) languages with Omega, a 16-bit extension of Donald Knuth’s TeX. In principle, Omega has no difficulty in typesetting those East Asian languages because of its internal representation using 16-bit Unicode. However, it has not been widely used in practice because of the difficult...

We have studied the thermoelectric characteristics of Si/GeAu superlattice thin films at temperatures ranging from 290 K to 75 K and compared them to those of the SiGeAu alloy thin film. In the annealed Si/GeAu superlattice, the electrical resistivity was lower than that of the unannealed Si/GeAu superlattice at all temperatures. The annealed Si/Ge...

We examined the magnetic field effects on thermoelectric properties, aiming to enhance the thermoelectric power generation. Here, we propose the "Nernst-Seebeck" element, which uses the hybrid electric field of the Seebeck effect and the Nernst effect in the magnetic field. The thermoelectric properties of the polycrystalline bismuth (Bi) in the ma...

Since the Peltier current lead (PCL) was proposed to reduce heat leakage in low-temperature systems, numerical calculations and experimental studies have been performed. However, these studies were done for the direct current (DC) mode because the applications of superconducting systems are mainly used in DC mode. On the other hand, since commercia...

After the Peltier current lead (PCL) was proposed to reduce heat leakage into a low-temperature system and demonstration experiments were performed for liquid helium systems, we study in this paper a PCL application to a liquid helium free magnet (HFM). Numerical calculation codes have been developed previously to optimize the current lead and to a...

Peltier current leads (PCLs) for cryogenic systems are investigated in regard to temperature dependence of thermoelectric materials. Due to the Peltier effect on the thermoelectric parts of the current lead, PCLs act as heat pumps. It is expected that PCLs will reduce the amount of heat leak from the room temperature side to the low temperature sid...

There are several different computer systems in LHD (Large Helical Device) experiment, and therefore the coalition of these computers is a key to perform the experiment. Real-time monitoring system is also important because the long discharge is needed in the LHD experiment. In order to achieve these two requirements, the technique of IP multicast...

This tutorial explains how to prepare PDF and PostScript manuscripts for online submissions to journals and e-Print archives using either LATEX or your favorite word-processing software.

Current imbalance can be estimated by the solution of the circuit equation, which depends on the result of the measurement of the self- and mutual inductances. Strand circuit is coupled with each other strongly, and therefore the matrix calculation is stiff. This situation leads to enhance the error of the measurement. In order to study this proble...

Peltier current leads (PCLs) are numerically analyzed. They consist of a thermoelectric element (TE) inserted into a pure copper lead at its room temperature end, with or without a high-Tc superconductor below 77 K. We solve a one-dimensional heat conduction equation to study their thermal behavior under the self-cooling condition. Each section of...

We have been investigating the current imbalance problem comparing the calculated result obtained by the measurement of inductance distribution in multi-strand superconducting cable conductor using high accuracy LCR meter and the measured actual current distribution in it. So far, the measurement of inductance and that of actual current had been ca...

Peltier current leads (PCL) are numerically analyzed. We solve a one-dimensional heat conduction equation to study the thermal behavior of a variety of PCLs under various cooling conditions. The PCLs consist of a thermoelectric element inserted into a copper lead at its room temperature end, with or without a high-T_c superconductor below...

The Peltier current lead (PCL) has been studied since it was proposed as one of the thermoelectric applications. Due to the Peltier effect, it is expected that the PCL reduces the heat leak from the room temperature side to the low temperature side of a cryogenic system. Thermoelectric materials are installed into the copper (or aluminum) leads at...

Several computer systems in NIFS (the National Institute for Fusion Science) are involved in the operation of the LHD (Large Helical Device) for plasma experiments. Because these systems are independent of each other, it is burdensome to the programmers and the researchers to use several of them for one project. Currently, the programmers must writ...

The large helical device (LHD) is a superconducting magnet system, created for the performance of plasma-fusion experiments, with an operation time of over a half-year for one cycle and long discharge being one of its main missions. We have developed a new monitoring system for data acquisition dedicated to the special characteristics of the LHD. H...

We have been investigating a current imbalance in multi-strand cable conductor using several types of solenoid coils wound by insulated multi-stranded copper cable, and obtained a result that the current distribution in the multi-stranded conductor is strongly affected by the magnetic coupling coefficient between strands. This time, we have carried...

The measurement of the Seebeck coefficient and resistivity was performed for a direction of the axis of the single crystal of bismuth-antimony in a magnetic field. The magnetic field effects were observed experimentally. We calculated the shape effects on the sample of the magnetic field using a two-dimensional computer code; effects studied includ...

We present a theoretical and computational framework for calculating transport properties of thermoelectric and thermomagnetic semiconductors and relating them to measurements. Assuming a multiple-band model with generally nonparabolic band structures, we numerically integrate the Boltzmann equation with a relaxation time approximation to obtain th...

Phenomenological equations describing the Seebeck, Hall, Nernst, Peltier, Ettingshausen, and Righi-Leduc effects are numerically solved for the temperature, electric current, and electrochemical potential distributions of semiconductors under magnetic field. The results are compared to experiments

This chapter constructs a flexible and extensible UNIX-based distributed monitoring system, consisting of data acquisition, distribution and monitoring subsystems. The acquisition subsystems transmit signals from physical targets by network multicasting. These signals and derived quantities (such as flow rate) are reconstructed on each network-conn...

Current leads, which connect superconducting magnets at the liquid helium temperature and power supplies at the room temperature, are the major source of heat leaking into cryostats, and therefore largely determines the running cost of magnet systems. Heat leak can be reduced by using high-temperature superconductors as the low-temperature (4 K-77...

NIFS (National Institute for Fusion Science) is engaged in developing a real-time monitoring system for their LHD (Large Helical Device) experiments. The system allows users to remotely participate in the experiments. The monitoring system is utilizing Java technology to accomplish these tasks. Some of the tasks include the ability to monitor exper...

The ultra-wideband real-time data acquisition (DAQ) system has started its operation at LHD steady-state experiments since 2004. It uses CompactPCI standard digitizers whose acquisition performance is continuously above 80 MB/s for each frontend, and is also capable of grabbing picture frames from high-resolution cameras. Near the end of the 8th LH...

資料 / Information 本研究では、情報ネットワークを用いたTV会議システムを利用した遠隔授業の実践の詳細を報告するとともに、このような授業を受講した生徒の授業に対する評価について検討を行った。本研究では、遠隔授業の実践として、大学の講義を高校生が受講するという出前授業の形を取り、学校情報「くものす」ネットワークと三重研究ネットワークを三重県総合教育センターで接続して行った。また、双方向授業は、TV会議システムだけではなく、E-mailをもちいても行われた。生徒からの評価としては、双方向のやりとりに関して好意的な感想が寄せられた一方、環境面への不満も寄せられた。質問紙による検討では、学習環境の中でも、特に「基本的設備」と呼ぶべきものが、学習への関与に関連していることが見いだされた。

オープンソースのコース(授業)管理システムMoodleをカスタマイズした三重大学Moodleを構築し、正式オープン以来すでに1年2か月運用してきた。ここではシステムの概要と利用状況や運用上の問題点を述べる。

In fusion experiments, diagnostic control and logging devices are usually connected through the field bus, e.g. GP-IB. Internet technologies are often applied for their remote operation. All equipment and digitizers are driven by pre-programmed sequences, in which clocks and triggers give the essential timing for data acquisition. Data production r...