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Your search keyword '"Kasahara, Hirofumi"' showing total 143 results
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143 results on '"Kasahara, Hirofumi"'

6. Stable sustainment of plasmas with electron internal transport barrier by ECH in the LHD

Author

YOSHIMURA, Yasuo, KASAHARA, Hirofumi, TOKITANI, Masayuki, SAKAMOTO, Ryuichi, Ueda, Y., MARUSHCHENKO, Nikolai B., SEKI, Ryosuke, KUBO, Shin, SHIMOZUMA, Takashi, IGAMI, Hiroe, TAKAHASHI, Hiromi, Tsujimura, Ii Toru, MAKINO, Ryohei, KOBAYASHI, Sakuji, ITO, Satoshi, MIZUNO, Yoshinori, OKADA, Kohta, AKIYAMA, Tsuyoshi, TANAKA, Kenji, TOKUZAWA, Tokihiko, YAMADA, Ichihiro, YAMADA, Hiroshi, MUTOH, Takashi, TAKEIRI, Yasuhiko, LHD, Experiment Group, YOSHIMURA, Yasuo, KASAHARA, Hirofumi, TOKITANI, Masayuki, SAKAMOTO, Ryuichi, Ueda, Y., MARUSHCHENKO, Nikolai B., SEKI, Ryosuke, KUBO, Shin, SHIMOZUMA, Takashi, IGAMI, Hiroe, TAKAHASHI, Hiromi, Tsujimura, Ii Toru, MAKINO, Ryohei, KOBAYASHI, Sakuji, ITO, Satoshi, MIZUNO, Yoshinori, OKADA, Kohta, AKIYAMA, Tsuyoshi, TANAKA, Kenji, TOKUZAWA, Tokihiko, YAMADA, Ichihiro, YAMADA, Hiroshi, MUTOH, Takashi, TAKEIRI, Yasuhiko, and LHD, Experiment Group

Abstract

The long pulse experiments in the Large Helical Device has made progress in sustainment of improved confinement states. It was found that steady-state sustainment of the plasmas with improved confinement at the core region, that is, electron internal transport barrier (e-ITB), was achieved with no significant difficulty. Sustainment of a plasma having e-ITB with the line average electron density ne_ave of 1.1 × 1019 m−3 and the central electron temperature Te0 of ∼3.5 keV for longer than 5 min only with 340 kW ECH power was successfully demonstrated., source:Citation Y Yoshimura et al 2018 Plasma Phys. Control. Fusion 60 025012, source:https://doi.org/10.1088/1361-6587/aa9950, identifier:0000-0001-6744-1829

Published
2021

10. AC losses in long Bi-2223 tapes wound into a solenoidal-coil

Author

Kasahara, Hirofumi, Sumiyoshi, Fumio, Kawagoe, Akifumi, Kubota, Kazuto, and Akita, Shirabe

Subjects
Solenoids -- Testing, Magnetic tapes -- Electric properties, Reel-to-reel tape -- Electric properties, High temperature superconductors -- Electric properties, Business, Electronics, Electronics and electrical industries
Abstract

Electrical loss measurements are carried out in liquid nitrogen for long Bi-2223 tapes wound into a solenoidal coil under various external conditions of ac transport currents and ac magnetic fields. A new measuring-system, which is an extension of our original measuring system applicable to short and straight HTS tapes, is developed.

Published
2004

17. Development of an Nb3Sn AC coil with react & wind method

Author

Kasahara, Hirofumi, Torii, Shinji, Akita, Shirabe, Kubota, Youji, Yasohama, Kazuhiko, Kobayashi, Hisayasu, Ogasawara, Takeshi, Kumano, Tomoyuki, and Miyake, Sei-ichi

Subjects
Electrical cables -- Design and construction, Electric conductors -- Design and construction, Electric coils -- Design and construction, Business, Electronics, Electronics and electrical industries
Abstract

The [Nb.sub.3]Sn superconductor possesses a higher critical temperature than the NbTi strand. Therefore, it is now possible to make highly stable superconducting strands. We examined the manufacturing process of AC [Nb.sub.3]Sn strands. The internal Sn diffusion process showed a higher critical current density than the conventional process. [Nb.sub.3]Sn strands for AC use have a high Jc with low temperature reaction heat treatment, because they have fine filaments to decrease AC loss. We made a 400kVA class superconducting coil using the developed [Nb.sub.3]Sn cable with the React & Wind method. The loss density of this coil was 25.7MW/[m.sup.3] at the point just before the quench. In this case, the temperature of the cable increases about 3.39K. This means that the coil using [Nb.sub.3]Sn cables has a very high stability in AC use.

Published
1996

18. Development of 100kVA AC superconducting coil using NbTi cables with a CuSi alloy matrix

Author

Kasahara, Hirofumi, Akita, Shirabe, Torii, Shinji, Sugimoto, Masahiro, Matsumoto, Kaname, Tanaka, Yasuzou, and Tachikawa, Kyoji

Subjects
High temperature superconductors -- Evaluation, Electrical cables -- Evaluation, Solenoids -- Design and construction, Business, Electronics, Electronics and electrical industries
Abstract

For implementation of AC superconducting equipment, it is imperative to develop low loss cables having highly stable characteristics. Here, newly developed NbTi superconducting cables using a CuSi alloy matrix are of low loss and are very promising as cables for practical application. However, since the CuSi alloy is a new material as a matrix for NbTi superconducting cables, many unknown factors as regards to optimum conditions for the manufacture of long cables, as well as superconducting characteristics are involved. For this new superconducting cable, a long strand (km class) was manufactured as a step for practical application, and a primary twisted cable was fabricated. Using this cable, a coil of the 100kVA class was fabricated for trial, and its performance characteristic with transport current was evaluated. This coil had no training phenomenon and had a high stabilities. Furthermore, it permitted full AC current transmission of up to DCIc. Upon analysis of the coil loss, the hysteresis loss was smaller than coupling loss, and there was little increase of loss due to the current flow to the coil. Consequently, by using CuSi alloy matrix superconducting cables, it was possible to provide an AC coil of low loss and high stability, and the present cable was found to be promising as a new AC superconducting cable in the future.

Published
1996

19. Critical currents of Nb3Sn superconductors for generators under cyclic mechanical load

Author

Kasahara, Hirofumi, Torii, Shinji, Akita, Shirabe, Uyeda, Kiyotaka, Ogawa, Tetsuji, Ikeno, Yoshimitsu, Inoue, Itaru, and Saito, Takashi

Subjects
Superconductors -- Research, Electric currents -- Research, Superconducting generators -- Research, Business, Electronics, Electronics and electrical industries
Abstract

Critical currents of [Nb.sub.3]Sn cabled superconductors were measured under cyclic mechanical compressive force of 30 MPa up to 10,000 times. The conductors were developed for a superconducting generator under the Super-GM project. The conductors were designed to apply the field winding of the 70 MW-class superconducting generator. The 10,000 repetitions of force application simulate 30 years of centrifugal and electromagnetic force produced by the daily start-and-stop (DSS) operation of the superconducting generator. In the test facility constructed at the Akagi Testing Center of the Central Research Institute of Electric Power Industry (CRIEPI), mechanical compressive force is generated by the cyclic fatigue test machine, which can generate 100 kN of force and is located on top of a cryostat at room temperature. Measured critical currents of two types of [Nb.sub.3]Sn conductor did not change throughout the test.

Published
1994

21. Multislice computed tomography is useful for evaluating partial anomalous pulmonary venous connection

Author

Tanami Yutaka, Aeba Ryo, Kasahara Hirofumi, and Yozu Ryohei

Subjects
Surgery, RD1-811, Anesthesiology, RD78.3-87.3
Abstract

Abstract Volume-rendered images, derived from multidetector-row computed tomography (MDCT), can facilitate assessment of the morphology of partial anomalous pulmonary venous connection and are thus useful in pre-operative planning to prevent surgical morbidity and assist post-operative evaluations.

Published
2010
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25. Recurrent infarctions due to a dome-shaped pannus above the mitral valve prosthesis

Author

Kasahara, Hirofumi, Inoue, Yoshito, and Suzuki, Satoru

Subjects
cardiovascular system, Case Report, cardiovascular diseases
Abstract

This report describes a unique case of a 56-year-old female who suffered from recurrent stroke after double mechanical valve replacement. During the four years after the surgery, she remained in normal sinus rhythm, received adequate anticoagulation therapy, and no apparent left atrial thrombus was detected. She underwent redo surgery to prevent further stroke after fourth instance of cerebral infarction. Intraoperative findings revealed a ‘dome-shaped’ pannus formation covering the sewing ring of the mitral prosthesis circumferentially, probably leading to clot formation and repeated infarctions. She has been stroke free for three years after pannus resection.

Published
2016

48. Biodegradable gelatin hydrogel potentiates the angiogenic effect of fibroblast growth factor 4 plasmid in rabbit hindlimb ischemia

Author

Kasahara, Hirofumi, primary, Tanaka, Etsuro, additional, Fukuyama, Naoto, additional, Sato, Eriko, additional, Sakamoto, Hiromi, additional, Tabata, Yasuhiko, additional, Ando, Kiyoshi, additional, Iseki, Harukazu, additional, Shinozaki, Yoshiro, additional, Kimura, Koji, additional, Kuwabara, Eriko, additional, Koide, Shirosaku, additional, Nakazawa, Hiroe, additional, and Mori, Hidezo, additional

Published
2003
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50. Development of Nb3Sn AC Coil. Manufacturing and Testing of AC Coil.

Author

KASAHARA, Hirofumi, primary, TORII, Shinji, additional, AKITA, Shirabe, additional, KUBOTA, Youji, additional, YASOHAMA, Kazuhiko, additional, KOBAYASHI, Hisayasu, additional, OGASAWARA, Takeshi, additional, KUMANO, Tomoyuki, additional, MIYAKE, Seiichi, additional, and ICHIHARA, Masamitsu, additional

Published
1995
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