Aoyama Gakuin University

About: Aoyama Gakuin University is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Superconductivity & Thin film. The organization has 3494 authors who have published 6419 publications receiving 115648 citations. The organization is also known as: Aoyama gakuin daigaku.

Smoothing Measured Displacements and Computing Strains Utilizing Finite Element Method

Abstract: A method for smoothing measured displacements and computing strains utilizing a finite element method is proposed. Nodal displacement values of a finite element model are determined by fitting the interpolation functions of finite elements to measured displacement values using the method of least-squares. Then, the smoothed displacement distributions are obtained. The displacements in the region where the measurement values are not obtained or unreliable are determined by solving finite element equations. The validity is demonstrated by applying the proposed method to displacements of a plate with a hole obtained by finite element method. Results show that the displacements and the strains can be determined accurately by the proposed method. Furthermore, the strains near free boundaries can be determined easily. As strains can be evaluated easily and accurately, it is expected that the proposed method can be applied to various problems in solid mechanics.

Comparative Study of the Initial Spikes of Soft Gamma-Ray Repeater Giant Flares in 1998 and 2004 Observed with Geotail: Do Magnetospheric Instabilities Trigger Large-Scale Fracturing of a Magnetar’s Crust?

Abstract: We present the unsaturated peak profile of the giant flare from SGR 1900+14 on 1998 August 27 This was obtained by the particle counters of the Low Energy Particles instrument on board the Geotail spacecraft The observed peak profile revealed four characteristic features: an initial steep rise, an intermediate rise to the peak, an exponential decay, and a small hump in the decay phase From this light curve, we found that the isotropic peak luminosity was 23 × 1046 ergs s-1 and that the total energy was 43 × 1044 ergs s-1 (E 50 keV), assuming that the distance to SGR 1900+14 is 15 kpc and that the spectrum is optically thin thermal bremsstrahlung with kT = 240 keV These values are consistent with the previously reported lower limits derived from Ulysses and Konus-Wind observations A comparative study of the initial spikes of the SGR 1900+14 giant flare in 1998 and of the SGR 1806-20 giant flare in 2004 is also presented The timescale of the initial steep rise shows a magnetospheric origin, while the timescale of the intermediate rise to the peak indicates that it originates from crustal fracturing Finally, we argue that the four features and their corresponding timescales provide us with a clue to identify extragalactic soft gamma-ray repeater giant flares among short gamma-ray bursts

Order N Monte Carlo Algorithm for Fermion Systems Coupled with Fluctuating Adiabatical Fields

Abstract: An improved algorithm is proposed for Monte Carlo methods to study fermion systems interacting with adiabatical fields. To obtain a weight for each Monte Carlo sample with a fixed configuration of adiabatical fields, a series expansion using Chebyshev polynomials is applied. By introducing truncations of matrix operations in a systematic and controlled way, it is shown that the cpu time is reduced from O ( N 3 ) to O ( N ) where N is the system size. Benchmark results show that the implementation of the algorithm makes it possible to perform systematic investigations of critical phenomena using system-size scalings even for an electronic model in three dimensions, within a realistic cpu timescale.