Yoshinori Sakamoto

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NAL Numerical Wind Tunnel (NWT) is a distributed memory parallel computer developed through joint research and development of NAL and Fujitsu. It is based on the analysis of CFD codes developed in NAL. The target performance is more than 100 times faster than VP400.In this paper, the parallel computation model employed in the development of the NWT is(More)
Dramatic increases in computing power and network speed, along with advances in sensing technology, have broadened the range of devices that can connect to the Internet. Large quantities of diverse, time-sequenced data are flowing in from the Web and countless sensors, and there is a strong demand to rapidly and efficiently extract any valuable information(More)
We calculate connected correlators in Gaussian orthogonal, unitary and symplectic random matrix ensembles by the replica method in the 1/N-expansion. We obtain averaged one-point Green's functions up to the next-to-leading order O(1/N) and wide two-level correlators up to the first non-trivial order O(1/N 2) by carefully treating fluctuations in(More)
The functional renormalization group for the random-field and random-anisotropy O(N) sigma models is studied to 2 loop. The ferromagnetic-disordered (F-D) transition fixed point is found to next order in d = 4 + epsilon for N > N(c) (N(c) = 2.834 740 8 for random field, N(c) = 9.441 21 for random anisotropy). For N < N(c) the lower critical dimension d =(More)
We calculate connected correlators in time dependent Gaussian orthogonal and symplectic random matrix ensembles by a diagrammatic method. We obtain averaged one-point Green's functions in the leading order O(N 0) and wide two-level and three-level correlators in the first nontrivial order by summing over twisted and untwisted planer diagrams. Introduction(More)
We study the critical phenomena of a random field O(N) spin model near the lower critical dimension, by means of the renormalization group method and the 1/N expansion. We treat the O(N) nonlinear σ model including a random field and all the random anisotropy terms, and calculate the one-loop beta function for a linear combination of them in d = 4+ 2 under(More)
Abstract. We reconsider stability of the non-trivial fixed point in 6− ǫ dimensional effective action for the random field Ising model derived by Brézin and De Dominicis. After expansion parameters of physical observables are clarified, we find that the nontrivial fixed point in 6 − ǫ dimensions is stable, contrary to the argument by Brézin and De(More)
We reexamine the effective action for the d-dimensional random field Ising model derived by Brézin and De Dominicis. We find a non-Gaussian fixed point where the φ4 couplings in the action have various scaling dimensions. The correlation-length exponent in d = 6 − ǫ has the value consistent with the argument of the dimensional reduction in the leading order.
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