Time filter

Source Type

Hiraiwa M.,Information and Telecommunication Systems Company | Masukawa H.,Network-1 | Nishimura S.,Japan Institute of Electrical Engineers
Hitachi Review | Year: 2010

OVERVIEW: The adoption of cloud computing in IT systems is driving even greater diversity in network services. The requirements for the networks that support IT systems going cloud include ensuring the level of reliability required to make services available via the network, keeping data as secure as if it were stored in-house even when the siting of data centers has become borderless, and improving the energy efficiency of equipment including that used in data centers and networking facilities. Hitachi is working on the construction of networks that support the use of cloud computing for services that feature a high level of security and reliability and are capable of delivering responsive performance efficiently and with high availability.


Shibata T.,Japan Institute of Electrical Engineers | Sudo K.,Business Management Division
Hitachi Review | Year: 2011

OVERVIEW: Concern for the global environment and the desire to use energy more efficiently are driving growing demand for lithium-ion batteries in industrial applications as well as in consumer products and automobiles. Application of lithium-ion batteries in industry requires the technical skills to be able to use them correctly and this in turn requires a good understanding not only of the batteries but also of the equipment and systems (load) to which power is being supplied. In addition to the batteries themselves, Hitachi has an extensive involvement with a wide range of products and systems such as power plants that act as the loads in these systems. Hitachi is taking advantage of this technical background to lead the world in commercializing these industrial systems.


Kadowaki K.,Japan Institute of Electrical Engineers | Takemura Y.,Kansai Electric Power Co. | Ozaki R.,University of Texas at Dallas
International Journal on Electrical Engineering and Informatics | Year: 2013

This paper presents an experimental study on repetitive partial discharge inception probability of twisted enameled wires subjected to modified inverter-surges. In order to obtain the probability curves as a function of the voltage amplitude, we develop an automatic measurement system of partial discharge inception probability for the twisted enameled wires subjected to the repetitive pulses with step-by-step increasing in the voltage height. Very fast oscillated pulses with or without polarity-reversal and an impulse-like pulse without oscillation are used as the modified inverter-surges. In the test for the impulse-like voltage, repetitive partial discharge inception voltage (RPDIV) decreases with increasing the pulse width. On the other hand, RPDIV for the polarity-reversed pulse with a higher oscillation cycle is lower than that for the pulse with lower oscillation cycle. The difference of PD inception probability between the voltage waveforms will be discussed on the basis of charge dynamics on the wire surfaces.


Ogasawara T.,Nippon Telegraph and Telephone | Ogasawara T.,Japan Institute of Electrical Engineers | Ogasawara T.,Institute of Electronics | Itoh Y.,Nippon Telegraph and Telephone | And 2 more authors.
NTT Technical Review | Year: 2016

NTT has developed a T-shirt type sensor that enables continuous measurement of the heart rate of the person wearing it. The sensor links to a smartphone, with which the user can easily see the measured heart rate variation. Vital signs such as heart rate variations will be more valuable when combined with information on the situation or activity context of the user. We developed a new method to analyze the user's gait information by using a three-axis acceleration sensor built into the T-shirt type sensor. We describe in this article the gait analysis procedure and an example of the result of continuous measurement for one day. This method is easily implemented as an application in a smartphone and enables simultaneous measurement of heart rate variation and gait information.


Saito T.,Japan Institute of Electrical Engineers | Hirashima Y.,Systems Development Laboratory | Yamamura H.,Enterprise Systems | Yoshida T.,Air Conditioning System Group
Hitachi Review | Year: 2010

OVERVIEW: Data centers house IT equipment centrally and run diverse IT services that form part of our social infrastructure, and factors such as their growing size and the increasing density of installed IT equipment have made the associated increase in power consumption a matter of concern around the world. It is believed that the solution to this problem can be found not only in reducing the power consumption of individual equipment but also through the coordinated control of all the equipment in the data center. Hitachi develops a range of different equipment and systems for data centers and in 2007 embarked on an "Environmentally Conscious Data Center Project" that draws on the overall capabilities of the Hitachi Group and an "IT Power-saving Plan" for reducing the power consumption of IT equipment. The major outcomes of this work to date have included the commercialization of a power supply unit for IT equipment and a spot cooling system that features natural circulation of the refrigerant. Future initiatives will include technology for collaborative control of IT and facilities which fits in with the overall aim of implementing center-wide control.


Oiwa T.,University of Shizuoka | Katsuki M.,Toshiba Corporation | Karita M.,Japan Institute of Electrical Engineers | Gao W.,Tohoku University | And 3 more authors.
International Journal of Automation Technology | Year: 2011

Surveys on ultra-precision positioning held seven times since 1986 are summarized in this paper. According to questionnaires in these surveys, including the latest in 2010, averaged recognition of "precision" is 1 μm and of "ultra-precision" 10 nm. Although positioning accuracy currently appears to have reached the development limit, accuracy under 1 nm is expected to be attained. Demand for higher speed, greater acceleration, and longer stroke increasing yearly has made the linear motor drive more popular. Improved displacement sensor performance now regularly uses the linear scale unit for practical reasons. Environmental concerns have led to hydraulic actuators being increasingly replaced by electromagnetic actuators, thus saving lubricating oil.


Shirani H.,Tokyo University of Agriculture and Technology | Nakamura Y.,Tokyo University of Agriculture and Technology | Nakamura Y.,Japan Institute of Electrical Engineers | Wakui S.,Tokyo University of Agriculture and Technology | Wakui S.,Japan Institute of Electrical Engineers
International Journal of Advanced Mechatronic Systems | Year: 2012

This paper considers a control scheme for the suppression of pneumatic isolation table's fluctuation induced by switching of the feedforward controller. The table acceleration and feedforward paths are added and the combined signal is sent to a damping integrator and gain. The damping integrator, besides generating a damping signal from acceleration signal, also avoids a large jump/drop of the feedforward signal during switching of the feedforward controller. Performance of this control scheme is evaluated by experiments while comparing with conventional control schemes. In addition, retuning of the feedforward compensator's gains is investigated. Based on the experimental results, it is shown that this control scheme can suppress both flow disturbances and switching of the feedforward controller.Copyright © 2012 Inderscience Enterprises Ltd.


Mikami H.,Japan Institute of Electrical Engineers | Ide K.,Hitachi Ltd. | Shimizu Y.,Hitachi Ltd. | Senoo M.,Japan Institute of Electrical Engineers | Seki H.,Japan Institute of Electrical Engineers
Hitachi Review | Year: 2011

Driven by a strong desire to produce electric motors using domestic rather than foreign technology, Hitachi's founder, Namihei Odaira, produced three 5-HP electric motors in 1910. Now,a century later, electric motors incorporate a variety of different technologies and have undergone significant changes in their size, performance, and other features. They have become a key device that underpins society in a wide range of fields including power generation, industry, transport, and home appliances.


Yamamoto K.,Chiba University | Maruyama T.,Chiba University | Kondo K.,Chiba University | Kashiwagi T.,Japan Institute of Electrical Engineers
Electronics and Communications in Japan | Year: 2015

Problems in high-power contactless power transmission systems using series and parallel resonance capacitors arise from the maximum voltage limit of the series capacitor due to high reactive power. In this study, the characteristics of the reactive power are analyzed using an equivalent circuit and a contactless power transfer system is designed with the reactive power characteristics taken into consideration. The self-inductance and the frequency can be used to determine the distribution of reactive power on the primary side and the secondary side. In addition, the optimal winding number, size of the coil, and the appropriate frequency are investigated through electromagnetic field analysis. © 2015 Wiley Periodicals, Inc.


Hiruma K.,Obayashi Corporation | Nihei T.,TOKYO TEKKO Co. | Sonehara T.,SHODEN Corporation | Yokoyama S.,Japan Central Research Institute of Electric Power Industry | Shimokawa H.,Japan Institute of Electrical Engineers
2014 International Conference on Lightning Protection, ICLP 2014 | Year: 2014

The Investigation and Research Committee of the Institute of Electrical Installation Engineers of Japan evaluated the performance of rebar used in the construction of buildings as down-conductors for lightning protection and determined that lightning current can be made to flow through rebar and joints that meet requirements. The authors measured the resistance of a building where rebar and joints were connected by lightning connectors and proved that the resistance was very low. © 2014 IEEE.

Loading Japan Institute of Electrical Engineers collaborators
Loading Japan Institute of Electrical Engineers collaborators