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306 results on '"Narumi, T."'

1. Petascale turbulence simulation using a highly parallel fast multipole method on GPUs

Author

Yokota, R., Barba, L. A., Narumi, T., and Yasuoka, K.

Subjects
Computer Science - Numerical Analysis, Physics - Computational Physics, Physics - Fluid Dynamics, 76F05, G.1.2, G.1.9
Abstract

This paper reports large-scale direct numerical simulations of homogeneous-isotropic fluid turbulence, achieving sustained performance of 1.08 petaflop/s on gpu hardware using single precision. The simulations use a vortex particle method to solve the Navier-Stokes equations, with a highly parallel fast multipole method (FMM) as numerical engine, and match the current record in mesh size for this application, a cube of 4096^3 computational points solved with a spectral method. The standard numerical approach used in this field is the pseudo-spectral method, relying on the FFT algorithm as numerical engine. The particle-based simulations presented in this paper quantitatively match the kinetic energy spectrum obtained with a pseudo-spectral method, using a trusted code. In terms of parallel performance, weak scaling results show the fmm-based vortex method achieving 74% parallel efficiency on 4096 processes (one gpu per mpi process, 3 gpus per node of the TSUBAME-2.0 system). The FFT-based spectral method is able to achieve just 14% parallel efficiency on the same number of mpi processes (using only cpu cores), due to the all-to-all communication pattern of the FFT algorithm. The calculation time for one time step was 108 seconds for the vortex method and 154 seconds for the spectral method, under these conditions. Computing with 69 billion particles, this work exceeds by an order of magnitude the largest vortex method calculations to date.

Published
2011
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2. Drift effects and the average features of cosmic ray density gradient in CIRs during successive two solar minimum periods

Author

Fushishita, A., Okazaki, Y., Narumi, T., Kato, C., Yasue, S., Kuwabara, T., Bieber, J. W., Evenson, P., Da Silva, M. R., Lago, A. Dal, Schuch, N. J., Tokumaru, M., Duldig, M. L., Humble, J. E., Sabbah, I., Kota, J., and Munakata, And K.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

We deduce on hourly basis the spatial gradient of the cosmic ray density in three dimensions from the directional anisotropy of high-energy (~50 GeV) galactic cosmic ray (GCR) intensity observed with a global network of muon detectors on the Earth's surface. By analyzing the average features of the gradient in the corotational interaction regions (CIRs) recorded in successive two solar activity minimum periods, we find that the observed latitudinal gradient (Gz) changes its sign from negative to positive on the Earth's heliospheric current sheet (HCS) crossing from the northern to the southern hemisphere in A<0 epoch, while it changes from positive to negative in A>0 epoch. This is in accordance with the drift prediction. We also find a negative enhancement in Gx after the HCS crossing in both A<0 and A>0 epochs, but not in Gy. This asymmetrical feature of Gx and Gy indicates significant contributions from the parallel and perpendicular diffusions to the the gradient in CIRs in addition to the contribution from the drift effect., Comment: 11 pages, 1 table, 5 figures, Proc. of AOGS 2008, accepted for the publication on the Advances in Geoscience, 2010

Published
2009
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4. Drift effects and the cosmic ray density gradient in a solar rotation period: First observation with the Global Muon Detector Network (GMDN)

Author

Okazaki, Y., Fushishita, A., Narumi, T., Kato, C., Yasue, S., Kuwabara, T., Bieber, J. W., Evenson, P., Da Silva, M. R., Lago, A. Dal, Schuch, N. J., Fujii, Z., Duldig, M. L., Humble, J. E., Sabbah, I., Kóta, J., and Munakata, K.

Subjects
Astrophysics
Abstract

We present for the first time hourly variations of the spatial density gradient of 50 GeV cosmic rays within a sample solar rotation period in 2006. By inversely solving the transport equation, including diffusion, we deduce the gradient from the anisotropy that is derived from the observation made by the Global Muon Detector Network (GMDN). The anisotropy obtained by applying a new analysis method to the GMDN data is precise and free from atmospheric temperature effects on the muon count rate recorded by ground based detectors. We find the derived north-south gradient perpendicular to the ecliptic plane is oriented toward the Helioshperic Current Sheet (HCS) (i.e. southward in the toward sector of the Interplanetary Magnetic Field (IMF) and northward in the away sector). The orientation of the gradient component parallel to the ecliptic plane remains similar in both sectors with an enhancement of its magnitude seen after the Earth crosses the HCS. These temporal features are interpreted in terms of a local maximum of the cosmic ray density at the HCS. This is consistent with the prediction of the drift model for the $A<0$ epoch. By comparing the observed gradient with the numerical prediction of a simple drift model, we conclude that particle drifts in the large-scale magnetic field play an important role in organizing the density gradient, at least in the present $A<0$ epoch. We also found that corotating interaction regions did not have such a notable effect. Observations with the GMDN provide us with a new tool for investigating cosmic ray transport in the IMF., Comment: 35 pages, 10 figures, submitted to the Astrophysical Journal

Published
2008
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14. Simulations of magnetic materials with MDGRAPE-2

Author

Elmegreen, B.G., Koch, R.H., Schabes, M.E., Crawford, T., Ebisuzaki, T., Furusawa, H., Narumi, T., Susukita, R., and Yasuoka, K.

Abstract

The use of accelerator hardware for micromagnetics simulations is described, along with some initial results. The accelerator calculates the dipole interactions at 400 gigaflops, allowing large simulations to be performed with arbitrary geometries. Two research programs are highlighted, the simulation of a curved MRAM cell and the simulation of the write head in a computer disk drive.

Published
2004

15. ICTを活用した外国語活動の授業づくりの支援（1） : 教員養成課程学生に対する意識調査の分析

Author

KASUYA,K, HASEGAWA,T, ITO,I, KIMURA,M, SHINDO,S, HAZEYAMA,A, KATO,N, NARUMI,T, FUJIWARA,Y, KURIHARA,S, SAITO,Y, HIRATA,Y, YOKOYAMA,A, FURUBAYASHI,S, KASUYA,K(Tokyo Gakugei University), HASEGAWA,T(Tokyo Gakugei University), ITO,I(Tokyo Gakugei University), KIMURA,M(Tokyo Gakugei University), SHINDO,S(Tokyo Gakugei University), HAZEYAMA,A(Tokyo Gakugei University), KATO,N(Tokyo Gakugei University), NARUMI,T(Tokyo Gakugei University), FUJIWARA,Y(Tokyo Gakugei University), KURIHARA,S(Attached Setagaya Elementary School of Tokyo Gakugei University), SAITO,Y(Attached Setagaya Elementary School of Tokyo Gakugei University), HIRATA,Y(Board of Education in Koganei-city), YOKOYAMA,A(Board of Education in Kodaira-city), and FURUBAYASHI,S(Board of Education in Kokubunji-city)

Subjects
Foreign Language Activity, ICT, Analysis of Poll, ETYP:教育関連論文
Published
2014

16. P3355Stress-induced left ventricular dyssynchrony predicts future cardiac events in patients with known or suspected coronary artery disease

Author

Katoh, S, primary, Watanabe, T, additional, Arimoto, T, additional, Narumi, T, additional, Aono, T, additional, Goto, J, additional, Sugai, T, additional, Takahashi, T, additional, Tamura, H, additional, Nishiyama, S, additional, Takahashi, H, additional, Shishido, T, additional, and Watanabe, M, additional

Published
2019
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17. P1626MicroRNA-21 deteriorates left ventricular reverse remodeling by promoting cardiac fibrosis in non-ischemic cardiomyopathy

Author

Watanabe, K, primary, Narumi, T, additional, Watanabe, T, additional, Aono, T, additional, Goto, J, additional, Sugai, T, additional, Toshima, T, additional, Kato, S, additional, Tamura, H, additional, Nishiyama, S, additional, Takahashi, H, additional, Arimoto, T, additional, Shishido, T, additional, and Watanabe, M, additional

Published
2019
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18. 東京学芸大学近隣3市教員に対するICT活用調査

Author

ITO,I., SHINDO,S., NARUMI,T., HAZEYAMA,A., KATO,N., ITO,I.(Department of Mathematics), SHINDO,S.(Department of Information Technology, Center for the Research and Support of Educational Practice), NARUMI,T.(Department of Science of Living), HAZEYAMA,A.(Department of Technology and Information Science), and KATO,N.(Department of Information Technology, Center for the Research and Support of Educational Practice)

Subjects
Questionnaire Study, Computerization in Education, Information Communication Technology, ETYP:教育関連論文
Published
2010

22. Annealing properties of open volumes in strained SiN films studied by monoenergetic positron beams.

Author

Uedono, A., Ito, K., Narumi, T., Sometani, M., Yamabe, K., Miyagawa, Y., Murata, T., Honda, K., Hattori, N., Matsuura, M., Asai, K., Ohdaira, T., and Suzuki, R.

Subjects
CHEMICAL vapor deposition, SILICON nitride, THIN films, POSITRON beams, ANNEALING of crystals
Abstract

The effect of annealing on open volumes in strained SiN films deposited on Si by plasma enhanced chemical vapor deposition was studied using monoenergetic positron beams. For compressive SiN, the stress was reduced by postdeposition annealing; this effect was attributed to the relaxation of matrix structures accompanied by an expansion of small open spaces intrinsically existing in the matrix and the introduction of large open volumes. For tensile SiN, although annealing tends to decrease the concentration of large open volumes, the size of the small open spaces and the film stress were almost constant up to 1000 °C annealing. This was attributed to the network structure related to the open spaces remaining stable even at 1000 °C annealing, and this mainly determines the stress in the tensile film. [ABSTRACT FROM AUTHOR]

Published
2007
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30. DRIFT EFFECTS AND THE AVERAGE FEATURES OF COSMIC RAY DENSITY GRADIENT IN CIRS DURING SUCCESSIVE TWO SOLAR MINIMUM PERIODS

Author

FUSHISHITA, A., primary, NARUMI, T., additional, KATO, C., additional, YASUE, S., additional, MUNAKATA, K., additional, OKAZAKI, Y., additional, KUWABARA, T., additional, BIEBER, J. W., additional, EVENSON, P., additional, DA SILVA, M. R., additional, DAL LAGO, A., additional, SCHUCH, N. J., additional, TOKUMARU, M., additional, DULDIG, M. L., additional, HUMBLE, J. E., additional, SABBAH, I., additional, and KÓTA, J., additional

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35. Roles and Effects of Human Network of Supporting Experts out of Niigata University to Practical Engineering Education.

Author

Oka, T., Abe, K., Yamauchi, T., Narumi, T., Ishii, N., Nishimura, S., Sato, T., Tanabe, Y., and Sengoku, M.

Subjects
EDUCATIONAL change, ENGINEERING education
Abstract

The educational supporting human network outside the university we call as "The network of 100 wises" has been constructed by Faculty of Engineering in Niigata University on the process of educational reform activities. We have operated various kinds of practical programs on engineering education which have been assisted by the engineers/scientists in private companies and the societies outside the university. Since the network members possess the various experiences through the processes of their practical R&D activities, the guidance, lectures, and advice by the network members are much beneficial for the university students as well as for the faculties engaged in the engineering education. The network is composed of the engineers/scientists of various generations and industrial areas, mainly based on the personal reliances with the faculties through their research collaborations. It is much advantageous for the university students to obtain the practical engineering skills and the ways of thinking by means of the cooperation with the network. [ABSTRACT FROM AUTHOR]

Published
2016
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44. Development of Positron Microbeam in AIST

Author

Oshima, Nagayasu, primary, Suzuki, Ryoichi, additional, Ohdaira, Toshiyuki, additional, Kinomura, Atsushi, additional, Narumi, T., additional, Uedono, Akira, additional, and Fujinami, M., additional

Published
2008
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45. Drift Effects and the Cosmic Ray Density Gradient in a Solar Rotation Period: First Observation with the Global Muon Detector Network (GMDN)

Author

Okazaki, Y., primary, Fushishita, A., additional, Narumi, T., additional, Kato, C., additional, Yasue, S., additional, Kuwabara, T., additional, Bieber, J. W., additional, Evenson, P., additional, Da Silva, M. R., additional, Dal Lago, A., additional, Schuch, N. J., additional, Fujii, Z., additional, Duldig, M. L., additional, Humble, J. E., additional, Sabbah, I., additional, Kóta, J., additional, and Munakata, K., additional

Published
2008
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50. Compressed exponential relaxation as superposition of dual structure in pattern dynamics of nematic liquid crystals.

Author

Narumi, T., Nugroho, F., Yoshitani, J., Hidaka, Y., Suzuki, M., and Kai, S.

Subjects
*SUPERPOSITION principle (Physics), *MOLECULAR dynamics, *MOLECULAR structure, *NEMATIC liquid crystals, *EXPONENTIAL functions, *TURBULENCE, *FLUCTUATIONS (Physics)
Abstract

Soft-mode turbulence (SMT) is the spatiotemporal chaos observed in homeotropically aligned nematic liquid crystals, where non-thermal fluctuations are induced by nonlinear coupling between the Nambu-Goldstone and convective modes. The net and modal relaxations of the disorder pattern dynamics in SMT have been studied to construct the statistical physics of nonlinear nonequilibrium systems. The net relaxation dynamics is well-described by a compressed exponential function and the modal one satisfies a dual structure, dynamic crossover accompanied by a breaking of time-reversal invariance. Because the net relaxation is described by a weighted mean of the modal ones with respect to the wave number, the compressed-exponential behavior emerges as a superposition of the dual structure. Here, we present experimental results of the power spectra to discuss the compressed-exponential behavior and the dual structure from a viewpoint of the harmonic analysis. We also derive a relationship of the power spectra from the evolution equation of the modal autocorrelation function. The formula will be helpful to study non-thermal fluctuations in experiments such as the scattering methods. [ABSTRACT FROM AUTHOR]

Published
2013
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